"So Gone" was written and produced by rapper Missy Elliott along with Kenneth Cunningham and Jamahl Rye from duo Spike & Jamahl. Recorded by Demacio Castellon at Hit Factory Criteria in Miami, Florida, the song was mixed by Scott Kieklak, while Marcella Araica and Javier Valeverde both assisted in the audio engineering of "So Gone". Backing vocals for the track were recorded by Monica, with additional vocals provided by fellow R&B singer Tweet. Built around a prominent sample from the 1976 song "You Are Number One", originally performed by American vocal group The Whispers, writer Zyah Ahmonuel holds partial songwriter credits on the song.