| United States Under Secretary of the Navy | |
|---|---|
 Seal of the Department of the Navy | |
 Flag of the Under Secretary of the Navy | |
since August 20, 2024 | |
| Department of the Navy | |
| Style | Mr. Under Secretary The Honorable (formal address in writing) |
| Reports to | Secretary of the Navy |
| Seat | The Pentagon, Arlington County, Virginia, United States |
| Nominator | The President with Senate advice and consent |
| Term length | No fixed term |
| Constituting instrument | 10 U.S.C. § 8015 |
| Formation | August 22, 1940 |
| First holder | James Forrestal |
| Succession | 17th in SecDef succession by seniority of appointment |
| Deputy | Deputy Under Secretary of the Navy |
| Salary | Executive Schedule, Level III[1] |
| Website | Official website |
The Under Secretary of the Navy is the second-highest ranking civilian official in the United States Department of the Navy. The Under Secretary, called the "Under" in Pentagon slang, reports to the Secretary of the Navy (SECNAV). Before the creation of the Under Secretary's office, the second-highest civilian at the Department of the Navy was the Assistant Secretary of the Navy.
The current acting Under Secretary of the Navy is Thomas Mancinelli.