(covers information from several alternate timelines)
Starfleet Administration (or simply Fleet Administration) was a Starfleet agency.
In the 2260s of the alternate reality, information on this agency was located in the Federation database. (Star Trek Beyond)
In the 24th century, this agency was mentioned by name on the dedication plaques of Miranda-class and Nebula-class starships.
Vice Admiral Brad Yacobian was noted for his work with Fleet Administration on the USS Brattain on stardate 22519.5. (TNG: "Night Terrors", dedication plaque)
Vice Admiral David Livingston was noted for his work with Fleet Administration on the USS Phoenix on stardate 40250.5. (TNG: "The Wounded", dedication plaque) He was later noted for his work on the USS Sutherland on stardate 44820.5. (TNG: "Redemption II", dedication plaque)