UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): October 31, 2013

Diamond Offshore Drilling, Inc.

(Exact Name of Registrant as Specified in Charter)

15415 Katy Freeway

Houston, Texas 77094

(Address of Principal Executive Offices and Zip Code)

Registrant’s telephone number, including area code: (281) 492-5300

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate line below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Item 8.01. Other Events

On October 31, 2013, Diamond Offshore Drilling, Inc. (the “Company”) issued a press release announcing the pricing of an offering of $250,000,000 aggregate principal amount of its 3.45% senior unsecured notes due November 1, 2023 and $750,000,000 aggregate principal amount of its 4.875% senior unsecured notes due November 1, 2043 pursuant to the Company’s shelf registration statement on Form S-3 (Registration No. 333-180004) filed with the Securities and Exchange Commission.

Filed herewith is a copy of such press release.

Statements in this report may contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements may include, without limitation, statements which project, indicate or imply future results and may contain words like “expect,” “intend,” “plan,” “will,” “estimated” and “budgeted,” among others. Such statements are inherently subject to a variety of assumptions, risks and uncertainties that could cause actual results to differ materially from those anticipated or projected. A discussion of the risk factors that could impact these areas and the Company’s overall business and financial performance can be found in the Company’s reports and other documents filed with the Securities and Exchange Commission. These factors include, among others, general economic and business conditions, changes in oil and natural gas prices, casualty losses, industry fleet capacity, changes in foreign and domestic oil and gas exploration and production activity, competition, changes in foreign, political, social and economic conditions, regulatory initiatives and compliance with governmental regulations, customer preferences and various other matters, many of which are beyond the Company’s control. Given these concerns, investors and analysts should not place undue reliance on forward-looking statements. Each forward-looking statement speaks only as of the date of this report. The Company expressly disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statement to reflect any change in the Company’s expectations with regard thereto or any change in events, conditions or circumstances on which any forward-looking statement is based.

Item 9.01. Financial Statements and Exhibits

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Company has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: October 31, 2013

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