Table of Contents

As filed with the Securities and Exchange Commission on July 22, 2014

1933 Act File No. 333 - 193497;1940 Act File No. 811–21593

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form N-2

and/or

Kayne Anderson MLP Investment Company

(Exact name of registrant as specified in charter)

811 Main Street, 14th Floor

Houston, TX 77002

(Address of Principal Executive Offices)

Registrant’s Telephone Number, Including Area Code: (877) 657-3863

David J. Shladovsky, Esq.

KA Fund Advisors, LLC

1800 Avenue of the Stars, Third Floor

Los Angeles, California 90067

(Name and Address of Agent for Service)

Approximate Date of Proposed Public Offering: From time to time after the effective date of the Registration Statement.

If any of the securities being registered on this form will be offered on a delayed or continuous basis in reliance on Rule 415 under the Securities Act of 1933, other than securities offered in connection with a dividend reinvestment plan, check the following box.     þ

It is proposed that this filing will become effective (check appropriate box):

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until this Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

Table of Contents

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any jurisdiction where the offer, solicitation or sale is not permitted.

BASE PROSPECTUS

Subject to completion, dated July 22, 2014

$ 1,000,000,000

Common Stock

Preferred Stock

Debt Securities

Kayne Anderson MLP Investment Company (the “Company,” “we,” “us,” or “our”) is a non-diversified, closed-end management investment company that began investment activities on September 28, 2004 following our initial public offering. Our investment objective is to obtain a high after-tax total return by investing at least 85% of our total assets in energy-related partnerships and their affiliates (collectively, “master limited partnerships” or “MLPs”), and in other companies that, as their principal business, operate assets used in the gathering, transporting, processing, storing, refining, distributing, mining or marketing of natural gas, natural gas liquids, crude oil, refined petroleum products or coal (collectively with MLPs, “Midstream Energy Companies”). We invest in equity securities of (i) master limited partnerships, including preferred, common and subordinated units and general partner interests, (ii) owners of such interests in master limited partnerships, and (iii) other Midstream Energy Companies. Additionally, we may invest in debt securities of MLPs and other Midstream Energy Companies. Substantially all of our total assets consist of publicly traded securities of MLPs and other Midstream Energy Companies. We are permitted to invest up to 50% of our total assets in unregistered or otherwise restricted securities of MLPs and other Midstream Energy Companies, including securities issued by private companies.

We may offer, from time to time, shares of our common stock ($0.001 par value per share), shares of our preferred stock ($0.001 par value per share), or debt securities, which we refer to in this prospectus collectively as our securities, in one or more offerings. We may offer our common stock, preferred stock or debt securities separately or in concurrent separate offerings, in amounts, at prices and on terms set forth in a prospectus supplement to this prospectus. You should read this prospectus and the related prospectus supplement carefully before you decide to invest in any of our securities.

We may offer and sell our securities to or through underwriters, through dealers or agents that we designate from time to time, directly to purchasers or through a combination of these methods. If an offering of our securities involves any underwriters, dealers or agents, then the applicable prospectus supplement will name the underwriters, dealers or agents and will provide information regarding any applicable purchase price, fee, commission or discount arrangements made with those underwriters, dealers or agents or the basis upon which such amount may be calculated. For more information about the manners in which we may offer our securities, see “Plan of Distribution.” We may not sell our securities through agents, underwriters or dealers without delivery of a prospectus supplement.

In addition, this prospectus relates to an offering of an aggregate principal amount of $400,000 of the Company’s Series HH Floating Rate Senior Notes due August 19, 2016 (the “Series HH Notes”) that may be made by selling noteholders referenced herein under the caption “Selling Noteholders.” Of the $400,000 aggregate principal amount of the Series HH Notes, $300,000 aggregate principal amount relates to an issue of $175,000,000 Series HH Notes completed on August 22, 2013 with obligations under a Registration Rights Agreement dated August 22, 2013 with respect thereto and $100,000 aggregate principal amount relates to an issue of $75,000,000 completed on February 7, 2014 with obligations under a Registration Rights Agreement dated February 7, 2014 with respect thereto. We will not receive any proceeds from the sale of the Series HH Notes by any of the selling noteholders.

We are managed by KA Fund Advisors, LLC (“KAFA”), a subsidiary of Kayne Anderson Capital Advisors, L.P. (together, with KAFA, “Kayne Anderson”), a leading investor in MLPs. As of November 30, 2013, Kayne Anderson and its affiliates managed approximately $25 billion, including approximately $16 billion in MLPs and other Midstream Energy Companies.

(continued on the following page)

Investing in our securities may be speculative and involve a high degree of risk and should not constitute a complete investment program. Before buying any securities, you should read the discussion of the material risks of investing in our securities in “Risk Factors” beginning on page 22 of this prospectus. You should consider carefully these risks together with all of the other information contained in this prospectus and any prospectus supplement before making a decision to purchase our securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is                 , 2014.

Table of Contents

(continued from the previous page)

Shares of our common stock are listed on the New York Stock Exchange (“NYSE”) under the symbol “KYN.” The net asset value of our common stock at the close of business on December 31, 2013 was $35.08 per share, and the last sale price per share of our common stock on the NYSE as of that date was $39.85. See “Market and Net Asset Value Information.”

Shares of common stock of closed-end investment companies, like ours, frequently trade at discounts to their net asset values. If our common stock trades at a discount to our net asset value, the risk of loss may increase for purchasers of our common stock, especially for those investors who expect to sell their common stock in a relatively short period after purchasing shares in this offering. See “Risk Factors — Additional Risks Related to Our Common Stock—Market Discount From Net Asset Value Risk.”

Our common stock is junior in liquidation and distribution rights to our debt securities and preferred stock. The issuance of our debt securities and preferred stock represents the leveraging of our common stock. See “Use of Leverage—Effects of Leverage,” “Risk Factors—Additional Risks Related to Our Common Stock—Leverage Risk to Common Stockholders” and “Description of Capital Stock.” The issuance of any additional common stock offered by this prospectus will enable us to increase the aggregate amount of our leverage. Our preferred stock is senior in liquidation and distribution rights to our common stock and junior in liquidation and distribution rights to our debt securities. Our debt securities are unsecured obligations and, upon our liquidation, dissolution or winding up, rank (i) senior to all of our outstanding common stock and any preferred stock; (ii) on a parity with our obligations to any unsecured creditors and any unsecured securities representing our indebtedness, including our outstanding senior notes and any notes that we may issue under this registration statement; and (iii) junior to our obligations to any secured creditors.

This prospectus is part of a registration statement that we have filed with the Securities and Exchange Commission (the “SEC”), using the “shelf” registration process. Under the shelf registration process, we may offer, from time to time, our common stock, preferred stock or debt securities, separately or in concurrent offerings, in amounts, at prices and on terms set forth in prospectus supplements to this prospectus. The securities may be offered at prices and on terms described in one or more supplements to this prospectus. This prospectus provides you with a general description of the securities that we may offer. Each time we use this prospectus to offer securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. This prospectus, together with any prospectus supplement, sets forth concisely the information about us that a prospective investor ought to know before investing. You should read this prospectus and the related prospectus supplement before deciding whether to invest and retain them for future reference. A Statement of Additional Information, dated                 , 2014 (the “SAI”), containing additional information about us, has been filed with the SEC and is incorporated by reference in its entirety into this prospectus. You may request a free copy of our SAI, the table of contents of which is on page      of this prospectus and our annual, semi-annual and quarterly reports to stockholders (when available), and request other information about the Company by calling toll-free at (877) 657-3863, or by writing to us at 811 Main Street, 14th Floor, Houston, Texas 77002, Attention: Investor Relations Department or by visiting our website at http://www.kaynefunds.com. The information contained in, or accessed through our website does not form part of this prospectus.

We file reports (including our annual, semi-annual and quarterly reports, and the SAI), proxy statements and other information with the SEC under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). Copies of such reports, proxy statements and other information, as well as the registration statement and the amendments, exhibits and schedules thereto, can be obtained from the SEC’s Public Reference Room in Washington, D.C. Information relating to the Public Reference Room may be obtained by calling the SEC at (202) 551-8090. Such materials, as well as the Company’s annual, semi-annual and quarterly reports and other information regarding the Company, are also available on the SEC’s website (http://www.sec.gov). You may also e-mail requests for these documents to publicinfo@sec.gov or make a request in writing to the SEC’s Public Reference Room, 100 F Street, N.E., Room 1580, Washington, D.C. 20549-0112.

None of our common stock, preferred stock or debt securities represent a deposit or obligation of, and are not guaranteed or endorsed by, any bank or other insured depository institution, and they are not federally insured by the Federal Deposit Insurance Corporation, the Federal Board or any other governmental agency.

Table of Contents

TABLE OF CONTENTS

You should rely only on the information contained or incorporated by reference in this prospectus and any related prospectus supplement. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted or where the person making the offer or sale is not qualified to do so or to any person to whom it is not permitted to make such offer or sale. You should assume that the information appearing in this prospectus and any prospectus supplement is accurate only as of the respective dates on their front covers, regardless of the time of delivery of this prospectus, any prospectus supplement, or any sale of our common stock. Our business, financial condition, results of operations and prospects may have changed since that date.

Table of Contents

PROSPECTUS SUMMARY

This summary highlights selected information contained elsewhere in this prospectus. This summary does not contain all of the information that you should consider before investing in our securities offered by this prospectus. You should carefully read the entire prospectus, any related prospectus supplement and the SAI, including the documents incorporated by reference into them, particularly the section entitled “Risk Factors” and the financial statements and related notes. Except where the context suggests otherwise, the terms the “Company,” “we,” “us,” and “our” refer to Kayne Anderson MLP Investment Company; “KAFA” or the “Adviser” refers to KA Fund Advisors, LLC; “Kayne Anderson” refers to KAFA and its managing member, Kayne Anderson Capital Advisors, L.P., collectively; “midstream energy assets” refers to assets used in the gathering, transporting, processing, storing, refining, distributing, mining or marketing of natural gas, natural gas liquids, crude oil, refined petroleum products or coal; “MLPs” or “master limited partnerships” refers to (i) energy-related partnerships, (ii) energy-related limited liability companies treated as partnerships and (iii) affiliates of those energy-related partnerships, substantially all of whose assets consist of interests in publicly traded partnerships; “Midstream Energy Companies” means (i) MLPs and (ii) other companies that, as their principal business, operate midstream energy assets; and “Energy Companies” means companies that own and operate assets that are used in or provide services to the energy sector, including assets used in exploring, developing, producing, transporting, storing, gathering, processing, refining, distributing, mining or marketing of natural gas, natural gas liquids, crude oil, refined products or coal.

The Company

Kayne Anderson MLP Investment Company, a Maryland corporation, is a non-diversified, closed-end management investment company registered under the Investment Company Act of 1940, as amended (the “1940 Act”). Our outstanding shares of common stock are listed on the New York Stock Exchange (the “NYSE”) under the symbol “KYN.”

We began investment activities in September 2004 following our initial public offering. As of December 31, 2013, we had approximately 100.6 million shares of common stock outstanding, net assets applicable to our common stock of approximately $3.5 billion and total assets of approximately $6.4 billion.

Investment Objective

Our investment objective is to obtain a high after-tax total return by investing at least 85% of our total assets in MLPs and other Midstream Energy Companies.

Investment Policies

We have adopted the following non-fundamental investment policies:

1

Table of Contents

Unless otherwise stated, all investment restrictions apply at the time of purchase and we will not be required to reduce a position due solely to market value fluctuations. However, although we may not be required to sell securities due to subsequent changes in value, if such changes cause us to have invested less than 80% of our total assets in securities of MLPs, we will be required to make future purchases of securities in a manner so as to bring us into compliance with this investment policy.

Our Board of Directors may change these investment policies without the approval of the holders of a majority of our voting securities, provided that our securities holders receive at least 60 days’ prior written notice of any change.

Our Investment Adviser

KA Fund Advisors, LLC (“KAFA” or the “Adviser”) is our investment adviser, responsible for implementing and administering our investment strategy. KAFA is a subsidiary of Kayne Anderson Capital

2

Table of Contents

Advisors, L.P. (“KACALP” and together with KAFA, “Kayne Anderson”). Both KAFA and KACALP are SEC-registered investment advisers. As of December 31, 2013, Kayne Anderson and its affiliates managed approximately $25 billion, including approximately $16 billion in MLPs and other Midstream Energy Companies. We believe that Kayne Anderson has developed an understanding of the MLP market that enables it to identify and take advantage of public MLP investment opportunities. In addition, Kayne Anderson’s senior professionals have developed a strong reputation in the energy sector and have many long-term relationships with industry managers, which we believe gives Kayne Anderson an important advantage in sourcing and structuring private investments.

KAFA manages three other publicly traded investment companies: Kayne Anderson Energy Total Return Fund, Inc. (NYSE: KYE); Kayne Anderson Energy Development Company (NYSE: KED); and Kayne Anderson Midstream/Energy Fund, Inc. (NYSE: KMF). Kayne Anderson has invested in MLPs and other Midstream Energy Companies since 1998.

The Offering

We may offer, from time to time, up to $1,000,000,000 of our securities at prices and on terms to be set forth in one or more prospectus supplements to this prospectus. In addition, this prospectus relates to an offering of an aggregate principal amount of $400,000 of the Company’s Series HH Floating Rate Senior Notes due August 19, 2016 (the “Series HH Notes”) that may be made by selling noteholders referenced herein under the caption “Selling Noteholders.” Of the $400,000 aggregate principal amount of the Series HH Notes, $300,000 aggregate principal amount relates to an issue of $175,000,000 Series HH Notes completed on August 22, 2013 with obligations under a Registration Rights Agreement dated August 22, 2013 with respect thereto and $100,000 aggregate principal amount relates to an issue of $75,000,000 completed on February 7, 2014 with obligations under a Registration Rights Agreement dated February 7, 2014 with respect thereto. We will not receive any proceeds from the sale of the Series HH Notes by any of the selling noteholders.

We may offer and sell our securities to or through underwriters, through dealers or agents that we designate from time to time, directly to purchasers or through a combination of these methods. If an offering of securities involves any underwriters, dealers or agents, then the applicable prospectus supplement will name the underwriters, dealers or agents and will provide information regarding any applicable purchase price, fee, commission or discount arrangements made with those underwriters, dealers or agents or the basis upon which such amount may be calculated. See “Plan of Distribution.” We may not sell any of our securities through agents, underwriters or dealers without delivery of a prospectus supplement describing the method and terms of the offering of our securities.

Use of Financial Leverage

We plan to utilize financial leverage with respect to our common stock through the issuance of preferred stock and debt securities, our revolving credit facility and other borrowings (such as term loans, prime brokerage or margin loans). The timing and terms of any leverage transactions will be determined by our Board of Directors. The issuance of additional common stock offered by this prospectus will enable us to increase the aggregate amount of our leverage. Throughout this prospectus, our debt securities, our revolving credit facility and other borrowings are collectively referred to as “Borrowings.”

We generally will seek to enhance our total returns through the use of financial leverage. Under normal market conditions, our policy is to utilize our Borrowings and our preferred stock, (each a “Leverage Instrument” and collectively “Leverage Instruments”) in an amount that represents approximately 30% of our total assets, including proceeds from such Leverage Instruments (which equates to approximately 56.7% of our net asset value as of December 31, 2013). However, based on market conditions at the time, we may use Leverage Instruments in amounts that represent greater than 30% leverage to the extent permitted by the 1940 Act. As of December 31, 2013, our Leverage Instruments represented approximately 26.5% of our total assets. At

3

Table of Contents

December 31, 2013, our asset coverage ratios under the 1940 Act, were 421% and 309% for debt and total leverage (debt plus preferred stock), respectively. Our long-term target asset coverage ratio with respect to our debt is 375%, but at times our target asset coverage ratios may be above or below this amount due to market conditions. For instance, our current target asset coverage ratio with respect to debt is 385%. Leverage Instruments have seniority in liquidation and distribution rights over our common stock. Costs associated with any issuance of preferred stock are borne immediately by common stockholders and result in a reduction of the net asset value of our common stock. See “Use of Leverage.”

Because our Adviser’s management fee is based upon a percentage of our average total assets, our Adviser’s fee is higher since we employ leverage. Therefore, our Adviser has a financial incentive to use leverage, which may create a conflict of interest between our Adviser and our common stockholders.

There can be no assurance that our leveraging strategy will be successful during any period in which it is used. The use of leverage involves significant risks and creates a greater risk of loss, as well as potential for more gain, for holders of our common stock than if leverage is not used. See “Risk Factors—Additional Risks Related to Our Common Stock—Leverage Risk to Common Stockholders” and “—Additional Risks Related to Our Preferred Stock—Senior Leverage Risk to Preferred Stockholders.”

Derivatives and Other Strategies

We currently expect to write call options with the purpose of generating realized gains or reducing our ownership of certain securities. We will only write call options on securities that we hold in our portfolio ( i.e. , covered calls). A call option on a security is a contract that gives the holder of such call option the right to buy the security underlying the call option from the writer of such call option at a specified price at any time during the term of the option. At the time the call option is sold, the writer of a call option receives a premium (or call premium) from the buyer of such call option. If we write a call option on a security, we have the obligation upon exercise of such call option to deliver the underlying security upon payment of the exercise price. When we write a call option, an amount equal to the premium received by us will be recorded as a liability and will be subsequently adjusted to the current fair value of the option written. Premiums received from writing options that expire unexercised are treated by us as realized gains from investments on the expiration date. If we repurchase a written call option prior to its exercise, the difference between the premium received and the amount paid to repurchase the option is treated as a realized gain or realized loss. If a call option is exercised, the premium is added to the proceeds from the sale of the underlying security in determining whether we have realized a gain or loss. We, as the writer of the option, bear the market risk of an unfavorable change in the price of the security underlying the written option.

We currently expect to utilize hedging techniques such as interest rate swaps to mitigate potential interest rate risk on a portion of our Leverage Instruments. Such interest rate swaps would principally be used to protect us against higher costs on our Leverage Instruments resulting from increases in short-term interest rates. We anticipate that the majority of our interest rate hedges will be interest rate swap contracts with financial institutions.

We may use short sales, arbitrage and other strategies to try to generate additional return. As part of such strategies, we may (i) engage in paired long-short trades to arbitrage pricing disparities in securities held in our portfolio; (ii) purchase call options or put options, (iii) enter into total return swap contracts; or (iv) sell securities short. Paired trading consists of taking a long position in one security and concurrently taking a short position in another security within the same or an affiliated issuer. With a long position, we purchase a stock outright; whereas with a short position, we would sell a security that we do not own and must borrow to meet our settlement obligations. We will realize a profit or incur a loss from a short position depending on whether the value of the underlying stock decreases or increases, respectively, between the time the stock is sold and when we replace the borrowed security. See “Risk Factors—Risks Related to Our Investments and Investment

4

Table of Contents

Techniques—Short Sales Risk.” A total return swap is a contract between two parties designed to replicate the economics of directly owning a security. We may enter into total return swaps with financial institutions related to equity investments in certain MLPs.

To a lesser extent, we may use various hedging and other risk management strategies to seek to manage market risks. Such hedging strategies would be utilized to seek to protect against possible adverse changes in the market value of securities held in our portfolio, or to otherwise protect the value of our portfolio. We may execute our hedging and risk management strategy by engaging in a variety of transactions, including buying or selling options or futures contracts on indexes. See “Risk Factors—Risks Related to Our Investments and Investment Techniques—Derivatives Risk.”

For purposes of determining compliance with the requirement that we invest 80% of our total assets in MLPs, we value derivative instruments based on their respective current fair market values. See “Investment Objective and Policies.”

Distributions

We have paid distributions to our common stockholders every fiscal quarter since inception and intend to continue to pay quarterly distributions to our common stockholders, funded in part by the net distributable income generated from our portfolio investments. The net distributable income generated from our portfolio investments is the amount received by us as cash or paid-in-kind distributions from equity securities owned by us, interest payments received on debt securities owned by us, other payments on securities owned by us, net premiums received from the sale of covered call options and income tax benefits, if any, less current or anticipated operating expenses, income tax expense, if any, and our leverage costs (including dividends on preferred stock issued by us and excluding non-cash amortization of costs to issue leverage). On January 10, 2014 we paid a quarterly distribution of $0.61per share to our common stockholders. Payment of future distributions is subject to approval by our Board of Directors, as well as meeting the covenants of our senior debt, the terms of our preferred stock and the asset coverage requirements of the 1940 Act. The Fund expects that a portion of its distributions may constitute a return of capital (“ROC”) distribution, which represents a return of a stockholder’s original investment in the Fund. See “Tax Matters—Federal Income Taxation of Holders of Our Common Stock.”

We pay dividends on the Series A MRP Shares, Series B MRP Shares, Series C MRP Shares, Series E MRP Shares, Series F MRP Shares and Series G MRP Shares (collectively, the “MRP Shares”) in accordance with the terms thereof. The holders of the Series A MRP Shares, Series B MRP Shares and Series C MRP Shares shall be entitled to receive quarterly cumulative cash dividends, and the holders of the Series E MRP Shares, Series F MRP Shares and Series G MRP Shares shall be entitled to receive monthly cumulative cash dividends, when, as and if authorized by the Board of Directors. The Series A MRP Shares pay dividends at a rate of 5.57% per annum, the Series B MRP Shares pay dividends at a rate of 4.53% per annum, the Series C MRP Shares pay dividends at a rate of 5.20% per annum, the Series E MRP Shares pay dividends at the rate of 4.25% per annum, the Series F MRP Shares pay dividends at the rate of 3.50% per annum and the Series G MRP Shares pay dividends at the rate of 4.60% per annum.

Use of Proceeds

Unless otherwise specified in a prospectus supplement, we intend to use the net proceeds of any sales of our securities pursuant to this prospectus to make investments in portfolio companies in accordance with our investment objective and policies, to repay indebtedness or for general corporate purposes. Pending such investments, we anticipate either investing the proceeds in short-term securities issued by the U.S. government or its agencies or instrumentalities or in high quality, short-term or long-term debt obligations or money market instruments. The supplement to this prospectus relating to an offering will more fully identify the use of proceeds from such offering. We will not receive any proceeds from any sale of Series HH Notes by the selling noteholders identified under “Selling Noteholders”. See “Use of Proceeds.”

5

Table of Contents

Taxation

We are treated as a corporation for federal income tax purposes and, as a result, we are subject to corporate income tax to the extent we recognize net taxable income. As a partner in MLPs, we report our allocable share of each MLP’s taxable income or loss in computing our taxable income or loss, whether or not we actually receive any cash from such MLP. See “Tax Matters.”

Stockholder Tax Features

Excluding the impact of any realized gains or realized losses, we expect that a portion of our distributions to our common stockholders may constitute a non-taxable return of capital distribution. If we make distributions from current and accumulated earnings and profits (which includes realized gains or realized losses, if any) as computed for federal income tax purposes, such distributions will generally be taxable to stockholders in the current period as ordinary income for federal income tax purposes and would be eligible for the lower tax rates applicable to qualified dividend income of non-corporate taxpayers under current law. If such distributions exceed our current and accumulated earnings and profits as computed for federal income tax purposes, such excess distributions will constitute a non-taxable return of capital to the extent of a common stockholder’s basis in our common stock and will result in a reduction of such basis. To the extent such excess exceeds a common stockholder’s basis in our common stock, such excess will be taxed as capital gain. A “return of capital” represents a return of a stockholder’s original investment in our shares, and should not be confused with a dividend from earnings and profits. Upon the sale of common stock, a holder of our common stock generally will recognize capital gain or loss measured by the difference between the sale proceeds received by the common stockholder and the common stockholder’s federal income tax basis in our common stock sold, as adjusted to reflect return of capital. See “Tax Matters.”

Risk Considerations

Investing in our securities involves risk, including the risk that you may receive little or no return on your investment, or even that you may lose part of all of your investment. Therefore, before investing in our securities you should consider carefully the risks set forth in “Risk Factors” beginning on page     . We are designed primarily as a long-term investment vehicle, and none of our common stock, preferred stock or debt securities is an appropriate investment for a short-term trading strategy. An investment in our securities should not constitute a complete investment program for any investor and involves a high degree of risk. Due to the uncertainty in all investments, there can be no assurance that we will achieve our investment objective.

Tax Risks

In addition to other risk considerations, an investment in our securities will involve certain tax risks, including the risk the master limited partnerships in which we invest will be classified as corporations rather than as partnerships for federal income tax purposes (which may reduce our return, negatively affect the net asset value of our common stock and negatively impact asset coverage ratios for our senior securities) and the risk of changes in tax laws or regulations, or interpretations thereof, which could adversely affect us or the portfolio companies in which we invest. Tax matters are very complicated, and the federal, state, local and foreign tax consequences of an investment in and holding of our securities will depend on the facts of each investor’s situation. Investors are encouraged to consult their own tax advisers regarding the specific tax consequences that may affect such investors. See “Risk Factors—Tax Risks” for more information on these risks.

Dividend Reinvestment Plan

We have adopted a dividend reinvestment plan for our common stockholders. Our plan is an “opt out” dividend reinvestment plan. As a result, if we declare a cash distribution to our common stockholders, then such distributions will be automatically reinvested in additional shares of our common stock, unless the stockholder

6

Table of Contents

specifically elects to receive cash. Common stockholders who receive distributions in the form of stock will be subject to the same federal, state and local tax consequences as common stockholders who elect to receive their distribution in cash. See “Dividend Reinvestment Plan.”

Trading at a Discount

The shares of common stock of closed-end investment companies frequently trade at prices lower than their net asset value. We cannot assure you that our common stock will trade at a price higher than or equal to our net asset value. The possibility that our common stock may trade at a discount to our net asset value is separate and distinct from the risk that our common stock’s net asset value may decline. In addition to net asset value, the market price of our common stock may be affected by such factors as the distributions we make, which are in turn affected by expenses, the stability of our distributions, liquidity and market supply and demand. If we were to issue our common stock at a price less than our net asset value (such offering would require the approval or our stockholders), our net asset value would be reduced immediately following such offering. See “Risk Factors,” “Description of Capital Stock” and “Our Structure; Common Stock Repurchases and Change In Our Structure.” Our common stock is designed primarily for long-term investors and you should not purchase our common stock if you intend to sell it shortly after purchase.

7

Table of Contents

FORWARD-LOOKING STATEMENTS

Certain statements in this prospectus constitute forward-looking statements, which involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by such forward-looking statements. Such factors include, among others, those listed under “Risk Factors” in this prospectus and our SAI. In this prospectus, we use words such as “anticipates,” “believes,” “expects,” “intends” and similar expressions to identify forward-looking statements.

The forward-looking statements contained in this prospectus include statements as to:

The factors identified above are believed to be important factors, but not necessarily all of the important factors, that could cause our actual results to differ materially from those expressed in any forward-looking statement. Unpredictable or unknown factors could also have material adverse effects on us. Since our actual results, performance or achievements could differ materially from those expressed in, or implied by, these forward-looking statements, we cannot give any assurance that any of the events anticipated by the forward-looking statements will occur, or, if any of them do, what impact they will have on our results of operations and financial condition. All forward-looking statements included in this prospectus are expressly qualified in their entirety by the foregoing cautionary statements. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this prospectus. We do not undertake any obligation to update, amend or clarify these forward-looking statements or the risk factors contained in this prospectus, whether as a result of new information, future events or otherwise, except as may be required under the federal securities laws. Although we undertake no obligation to revise or update any forward-looking statements, whether as a result of new information, future events or otherwise, you are advised to consult any additional disclosures that we may make directly to you or through reports that we in the future may file with the SEC, including our annual reports. We acknowledge that, notwithstanding the foregoing statement, the safe harbor for forward-looking statements under the Private Securities Litigation Reform Act of 1995 does not apply to investment companies such as us.

8

Table of Contents

KAYNE ANDERSON MLP INVESTMENT COMPANY

We are a non-diversified, closed-end management investment company registered under the 1940 Act. We were formed as a Maryland corporation in June 2004 and began investment activities in September 2004 after our initial public offering. Our common stock is listed on the NYSE under the symbol “KYN.”

As of December 31, 2013, we had (a) approximately 100.6 million shares of common stock outstanding, (b) $449 million of MRP Shares outstanding, (c) $64 million borrowed on our credit facility, and (d) $1,175 million in Senior Notes outstanding. As of December 31, 2013, we had net assets applicable to our common stock of approximately $3.5 billion and total assets of approximately $6.4 billion.

The following table sets forth information about our outstanding securities as of December 31, 2013 (the information in the table is unaudited; and amounts are in 000s):

Our principal office is located at 811 Main Street, 14th Floor, Houston, Texas 77002, and our telephone number is (713) 493-2020.

9

Table of Contents

FEES AND EXPENSES

The following table contains information about the costs and expenses that common stockholders will bear directly or indirectly. The table below assumes the use of Leverage Instruments in an amount equal to 26.3% of our total assets, which represents our average leverage levels for the fiscal year ended November 30, 2013, and shows our expenses as a percentage of net assets attributable to our common stock. We caution you that the percentages in the table below indicating annual expenses are estimates and may vary from actual results.

10

Table of Contents

The purpose of the table above and the example below is to help you understand all fees and expenses that you would bear directly or indirectly as a holder of our common stock. See “Management” and “Dividend Reinvestment Plan.”

Example

The following example illustrates the expenses that common stockholders would pay on a $1,000 investment in our common stock, assuming total annual expenses before tax are 4.67% of net asset value in year 1. The following example assumes that all distributions are reinvested at net asset value, an annual rate of return of 5% on our portfolio securities, and expenses include income tax expense associated with the 5% assumed rate of return on such portfolio securities.

THE EXAMPLE AND THE EXPENSES IN THE TABLE ABOVE SHOULD NOT BE CONSIDERED A REPRESENTATION OF FUTURE EXPENSES. The example assumes that the estimated “Annual Expenses (exclusive of current and deferred income tax expense)” set forth in the Annual Expenses table are accurate and that all distributions are reinvested at net asset value. ACTUAL EXPENSES (INCLUDING THE COST OF LEVERAGE, IF ANY, AND OTHER EXPENSES) MAY BE GREATER OR LESS THAN THOSE SHOWN. Moreover, our actual rate of return may be greater or less than the hypothetical 5% return shown in the example. IN THE EVENT THAT A SALES LOAD APPLIES, AN EXAMPLE SIMILAR TO THIS WILL BE RESTATED IN A CORRESPONDING PROSPECTUS SUPPLEMENT TO SHOW THE EFFECT OF THE SALES LOAD.

11

Table of Contents

FINANCIAL HIGHLIGHTS

The information in the following table is derived from our financial statements and financial highlights, the accompanying notes thereto, and the report of PricewaterhouseCoopers LLP thereon for the fiscal year ended November 30, 2013 (the “2013 Audited Financial Statements”) which are incorporated by reference into our SAI. Copies of our SAI are available from us without charge upon request.

12

Table of Contents