Exhibit 5.1

ALSTON&BIRD LLP

One Atlantic Center

1201 West Peachtree Street

Atlanta, Georgia 30309-3424

404-881-7000

Fax: 404-881-7777

www.alston.com

September 10, 2013

The Home Depot, Inc.

2455 Paces Ferry Road, N.W.

Atlanta, Georgia 30339

Ladies and Gentlemen:

We have acted as counsel to The Home Depot, Inc., a Delaware corporation (the “Company”), in connection with the issuance and sale by the Company to the several underwriters referenced below (the “Underwriters”) of $1,150,000,000 aggregate principal amount of the Company’s 2.250% Senior Notes due September 10, 2018, $1,100,000,000 aggregate principal amount of the Company’s 3.750% Senior Notes due February 15, 2024 and $1,000,000,000 aggregate principal amount of the Company’s 4.875% Senior Notes due February 15, 2044 (collectively, the “Notes”) to be issued under the Indenture dated as of August 24, 2012 (the “Indenture”) between the Company and Deutsche Bank Trust Company Americas, as trustee (the “Trustee”). The Company is selling the Notes to the Underwriters pursuant to the Underwriting Agreement dated September 3, 2013 (the “Underwriting Agreement”) by and among the Company and the representatives of the several underwriters named therein. We are furnishing the opinion set forth below pursuant to Item 16 of Form S-3 and Item 601(b)(5) of Regulation S-K of the Securities and Exchange Commission (the “Commission”).

In rendering the opinions set forth herein, we have examined the following documents and instruments (items (i) through (v) referred to herein as the “Transaction Documents”):

(i) the registration statement on Form S-3 (No. 333-183621) filed by the Company with the Commission pursuant to the Securities Act of 1933, as amended (the “Act”), including information deemed to be a part of the registration statement pursuant to Rule 430B of the Commission (the “Registration Statement”);

(ii) an executed copy of the Underwriting Agreement;

(iii) an executed copy of the Indenture;

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September 10, 2013

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(iv) the global certificates evidencing the Notes in the form delivered by the Company to the Trustee for authentication and delivery; and

(v) copies of certain resolutions of the Board of Directors of the Company adopted on August 22, 2013 and copies of certain resolutions of a Pricing Committee comprised of officers of the Company established by the Company’s Board of Directors adopted on September 3, 2013, each certified by Stacy S. Ingram, Assistant Secretary of the Company.

We have also examined such other agreements, instruments and other documents and such certificates of officers of the Company and of public officials, and have made such examination of law, as we have deemed necessary or appropriate for the purposes hereof.

As to certain factual matters, but not conclusions of law, we have relied upon the representations and warranties of the parties to the Transaction Documents and upon certificates of officers of the Company and of public officials. Except as otherwise expressly set forth, we have made no independent examination of facts, review of court records or other public records, or factual investigation for the purposes of this opinion letter.

For purposes of this opinion letter, we have assumed (i) the genuineness of all signatures; (ii) the authenticity of all documents submitted to us as originals; (iii) the conformity to the originals of all documents submitted to us as certified, conformed, photostatic, electronic or telefacsimile copies; (iv) the legal capacity of all natural persons; and (v) the due authorization, execution, and delivery of and the validity and binding effect of the Transaction Documents with regard to the parties to the Transaction Documents other than the Company.

We express no opinion herein in respect of any laws other than the General Corporation Law of the State of Delaware and the laws of the State of New York that, in our experience, are normally applicable to transactions of the type contemplated by the Transaction Documents.

Based upon the foregoing and subject to the other assumptions, exceptions, limitations and qualifications stated herein, we are of the opinion that the Notes, when duly authenticated by the Trustee and issued and delivered by the Company against payment therefor in accordance with the terms of the Underwriting Agreement and the Indenture, will be legally issued and will constitute valid and binding obligations of the Company enforceable against the Company in accordance with their terms and entitled to the benefits of the Indenture.

The foregoing opinion is subject to the effects of (i) bankruptcy, fraudulent conveyance or fraudulent transfer, insolvency, reorganization, moratorium, liquidation, conservatorship, and similar laws, and limitations imposed under judicial decisions, related to or affecting creditors’ rights and remedies generally, (ii) general equitable

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September 10, 2013

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principles, regardless of whether the issue of enforceability is considered in a proceeding in equity or at law, and principles limiting the availability of the remedy of specific performance, and (iii) concepts of good faith, fair dealing, materiality and reasonableness.

The opinion contained herein is limited to the matters expressly stated herein, and no opinion may be implied or inferred beyond the opinion expressly stated.

The foregoing opinion is rendered as of the date hereof, and we make no undertaking and expressly disclaim any duty to supplement or update such opinion if, after the date hereof, facts or circumstances come to our attention or changes in the law occur which could affect such opinion.

We hereby consent to the filing of this opinion letter with the Commission as an exhibit to the Company’s Current Report on Form 8-K being filed on the date hereof and incorporated by reference into the Registration Statement. We also hereby consent to the reference to our firm under the caption “Legal Matters” in the Prospectus Supplement dated September 3, 2013 filed by the Company with the Commission on September 4, 2013 and deemed to be a part of the Registration Statement. In giving this consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.