Exhibit 99.1 Contact: Kevin Bordosky Senior Director, Investor Relations (281) 647-4035 Diamond Offshore Reports Fourth Quarter 2023 Results HOUSTON, February 27, 2024 — Diamond Offshore Drilling, Inc. (NYSE: DO) today reported the following results for the fourth quarter of 2023: | Thousands of dollars, except per share data | | | Three Months Ended | | | --- | --- | --- | --- | --- | | | December 31, 2023 | | | September 30, 2023 | | Total revenues | $| 297,637 |$ | 244,958 | | Operating income | | 44,9 ...