UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

Amendment No. 1

x    ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

For The Fiscal Year Ended December 31, 2007

OR

¨    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF

THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from              to             

Commission File No. 001-14428

RENAISSANCERE HOLDINGS LTD.

(Exact Name Of Registrant As Specified In Its Charter)

Renaissance House, 8-20 East Broadway, Pembroke HM 19 Bermuda

(Address of Principal Executive Offices)

(441) 295-4513

(Registrant’s telephone number)

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer (as defined in Rule 405 of the Act).

Yes x    No ¨

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes ¨     No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes x    No ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, as defined in Rule 12b-2 of the Act. Large accelerated filer x, Accelerated filer ¨, Non-accelerated filer ¨, Smaller reporting company ¨

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).

Yes ¨    No x

The aggregate market value of Common Shares held by nonaffiliates of the registrant at June 29, 2007 was $4,446,505,998 based on the closing sale price of the Common Shares on the New York Stock Exchange on that date.

The number of Common Shares outstanding at February 12, 2008 was 65,686,769.

The information required by Part III of this report, to the extent not set forth herein, is incorporated by reference to the registrant’s Definitive Proxy Statement filed in respect of our 2008 Annual General Meeting of Shareholders.

EXPLANATORY NOTE

This Amendment No. 1 on Form 10-K/A (the “Form 10-K/A”) to the Annual Report on Form 10-K for RenaissanceRe Holdings Ltd. (the “Company”) for the year ended December 31, 2007, originally filed on February 22, 2008 (the “Original Form 10-K”), is being filed pursuant to and in compliance with the time requirements of Rule 3-09 of Regulation S-X to amend Item 15, Exhibits and Financial Statement Schedules, to include Exhibit 99.1, the audited financial statements of ChannelRe Holdings Ltd., a Bermuda company (“ChannelRe”), at December 31, 2007 and 2006 and for the years ended December 31, 2007, 2006 and 2005, including the related report of ChannelRe’s independent auditors. Item 15 is also being amended to file Exhibit 23.2, the consent of ChannelRe’s independent auditors related to their opinion contained in this filing. In accordance with Rule 12b-15 promulgated under the Securities Exchange Act of 1934, as amended, the text of the amended Item 15 is set forth in its entirety herein, including those portions of the text that have not been amended from that set forth in the Original Form 10-K. Additionally, in connection with the filing of this Form 10-K/A and pursuant to SEC rules, the Company is including currently dated certifications under Sections 302 and 906 of the Sarbanes–Oxley Act of 2002. This Form 10-K/A does not otherwise update any exhibits as originally filed and does not otherwise reflect events occurring after the original filing date of the Original Form 10-K. Accordingly, this Form 10-K/A should be read in conjunction with the Company’s filings with the SEC subsequent to the filing of the Original Form 10-K.

PART IV

ITEM 15.    EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

SIGNATURE

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, in Hamilton, Bermuda on June 30, 2008.

RENAISSANCERE HOLDINGS LTD.