In the United States, the title of first gentleman may be accorded to a man who is married to the head of state of a state government, analogously to the unofficial use of first lady for the wife or hostess of a head of state, including the wife of the president of the United States. Doug Emhoff became the first second gentleman of the United States when his wife Kamala Harris became vice president in 2021.

The first man formally to serve as first gentleman was James E. Ferguson in 1925, a former governor of Texas who was forced from office due to corruption charges, and whose wife Miriam A. Ferguson later won the office. The first man to serve as first gentleman without having previously served as governor was Thomas Grasso in 1975, husband of Connecticut governor Ella T. Grasso. In 2019, Colorado governor Jared Polis' husband Marlon Reis (who at the time was his partner), became the first same-sex partner to receive the title of First Gentleman (in addition to being the first same-sex partner of a sitting governor).

Even though Arizona has had the most female governors of any U.S. state with four female governors, only two of these governors were married to a first gentleman while in office. Six states have had more than one first gentleman: New Hampshire and Kansas, with three, and Arizona, Connecticut, Michigan, and Oregon, all numbering two.