Exhibit 5.1

May 11, 2015

Harman International Industries, Incorporated

400 Atlantic Street, Suite 1500

Stamford, Connecticut 06901

Registration Statement on Form S-3

File No. 333- 203760

Ladies and Gentlemen:

We have acted as counsel to Harman International Industries, Incorporated, a Delaware corporation (the “Company”), in connection with the registration, pursuant to a Registration Statement on Form S-3 (File No. 333-203760) (the “Registration Statement”), filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), of the offering and sale by the Company of $400,000,000 aggregate principal amount of 4.150% Notes due 2025 (the “Securities”) of the Company to be issued under an Indenture (the “Base Indenture”) dated as of May 11, 2015, between the Company and U.S. Bank National Association, as Trustee, as supplemented by the First Supplemental Indenture (the “Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), dated as of May 11, 2015 between the Company and the Trustee, and sold pursuant to the terms of an underwriting agreement (the “Underwriting Agreement”), dated May 6, 2015, between the Company and J.P. Morgan Securities LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated, and Wells Fargo Securities, LLC, as representatives of the underwriters named therein (the “Underwriters”). This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

We have examined originals or certified copies of such corporate records of the Company and other certificates and documents of officials of the Company, public officials and others as we have deemed appropriate for purposes of this letter. We have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals, the conformity to authentic original documents of all copies submitted to us as conformed, certified or reproduced copies, and that the Securities will conform to the specimen thereof we have reviewed. We have also assumed that the Indenture is a valid and binding obligation of the Trustee, enforceable against the Trustee in accordance with its terms. As to various questions of fact relevant to this letter, we have relied, without independent investigation, upon certificates of public officials and certificates of officers of the Company, all of which we assume to be true, correct and complete.

One Bryant Park | New York, New York 10036-6745 | 212.872.1000 | fax: 212.872.1002 | akingump.com

Harman International Industries, Incorporated

May 11, 2015

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Based upon the foregoing and subject to the assumptions, exceptions, qualifications and limitations set forth herein, we are of the opinion that when the Securities have been duly executed by the Company, duly authenticated by the Trustee in accordance with the terms of the Indenture, and delivered to and paid for by the Underwriters pursuant to the terms of the Underwriting Agreement, the Securities will be valid and binding obligations of the Company.

The opinions and other matters in this letter are qualified in their entirety and subject to the following:

Harman International Industries, Incorporated

May 11, 2015

Page 3

We hereby consent to the filing of this opinion as an exhibit to a Current Report on Form 8-K filed by the Company with the Commission on or about the date hereof, to the incorporation by reference of this opinion into the Registration Statement and to the use of our name in the Prospectus dated April 30, 2015, and the Prospectus Supplement dated May 6, 2015, forming a part of the Registration Statement under the caption “Legal Matters.” In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act and the rules and regulations thereunder.