Borr Drilling Ltd美股招股说明书(2025-12-08版)

The information in this preliminary prospectus supplement and the accompanying prospectusis not complete and may be changed. This preliminary prospectus supplement and theaccompanying prospectus are not an offer to sell these securities and are not soliciting an offerto buy these securities in any jurisdiction where the offer or sale is not permitted. Filed Pursuant to Rule424(b)(5)Registration No. 333-286490 Subject to completion, dated December8, 2025 PRELIMINARY PROSPECTUS SUPPLEMENT(To prospectus dated April 11, 2025) 21,000,000 Common Shares Borr Drilling Limited We are offering 21,000,000 of our common shares, par value $0.10 per share (the “Offering”). Our commonshares are listed on the New York Stock Exchange, or the NYSE, under the ticker symbol “BORR.” OnDecember 5, 2025, the last reported sale price of our common shares on the NYSE was $4.05 per share. Weintend to use the net proceeds from this Offering, together with the proceeds from the Debt Offering and theSeller Financing (each as defined herein) and, if necessary, available cash, for the acquisition of five premiumjack-up rigs as described herein (the “Acquisition”), and for general corporate purposes, which may include debtservice, capital expenditures, funding of our working capital and potential mergers and acquisitions. See “Use ofProceeds.” This Offering and the Debt Offering are not conditioned upon the completion of the Acquisition or thecompletion of any of the financings or other transactions contemplated in connection with the Acquisition. Theclosing of this Offering and the Debt Offering will occur prior to the consummation of the Acquisition. You should carefully read this prospectus supplement and the accompanying prospectus, together with thedocuments we incorporate by reference, before you invest in our common shares. We also encourage you to readthe documents we have referred you to in the “Where You Can Find More Information” section of this prospectussupplement. Investing in our common shares involves risks. Before making an investment decision, please read theinformation contained in and incorporated by reference under the heading “Risk Factors” on page S-12ofthis prospectus supplement and on page8of the accompanying prospectus, and beginning on page 7 of ourAnnual Report on Form20-F for the year ended December 31, 2024, and under similar headings in theother documents that we have filed or that are filed after the date hereof and incorporated by referenceinto this prospectus supplement and the accompanying prospectus. Neither the Securities and Exchange Commission (“SEC”) nor any state securities commission hasapproved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectussupplement or the accompanying prospectus. Any representation to the contrary is a criminal offense. (1)In addition, the Company may at its election and in its absolute discretion pay to certain of the Underwriters a discretionary cash fee ofup to 0.75% of the aggregate gross proceeds received by the Company in the Offering. The underwriters expect to deliver the common shares to purchasers on or about December, 2025 (the“Settlement Date”). TABLE OF CONTENTS Prospectus Supplement PageABOUT THIS PROSPECTUS SUPPLEMENTS-1SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSS-3PROSPECTUS SUPPLEMENT SUMMARYS-6RISK FACTORSS-12USE OF PROCEEDSS-17CAPITALIZATIONS-18THE ACQUISITIONS-20INDUSTRY AND MARKET OVERVIEWS-22UNDERWRITINGS-27EXPENSES RELATED TO THIS OFFERINGS-32LEGAL MATTERSS-33EXPERTSS-34WHERE YOU CAN FIND MORE INFORMATION ABOUT USS-35INCORPORATION OF DOCUMENTS BY REFERENCES-36 ABOUT THIS PROSPECTUS1WHERE YOU CAN FIND MORE INFORMATION ABOUT US2INCORPORATION OF DOCUMENTS BY REFERENCE3SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS4OUR COMPANY7RISK FACTORS8USE OF PROCEEDS9DESCRIPTION OF COMMON SHARES10DESCRIPTION OF PREFERENCE SHARES14DESCRIPTION OF DEBT SECURITIES15DESCRIPTION OF WARRANTS21DESCRIPTION OF RIGHTS23DESCRIPTION OF UNITS24SELLING SECURITY HOLDERS25PLAN OF DISTRIBUTION26EXPENSES28TAXATION29ENFORCEABILITY OF CIVIL LIABILITIES30LEGAL MATTERS31EXPERTS32 TABLE OF CONTENTS ABOUT THIS PROSPECTUS SUPPLEMENT This document contains two parts. The first part is this prospectus supplement, which describes the specific terms ofthis Offering and the common shares offered hereby, and also adds to and updates information contained in theaccompanying prospectus and the documents incorporated by reference. The second part, the accompanyingprospectus, gives more general information about us, some of which may not apply to this Offering. This prospectussupplement is deemed to be incorporated by reference into the accompanying prospectus solely for the purpose ofthis Offering. When we refer to the “prospectus,” we are referring to both parts combined and when we refer to theaccompanying prospectus we are referring to the base prospectus. If there is any inconsistency between information in or incorporated by r