"Say So" was written by PJ Morton while also handling the song's production for his sixth studio album Paul (2019).

Morton also handled majority of the song's instrumentation except for bass which was played by DJ Raymond.

[1] The mixing of "Say So" was done by Kevin “KD” Davis at Larrabee Studios in Los Angeles, California and eventually, the mastering was done by Will Quinnell at Sterling Sound in New York.

[1][4][5][6] The music video for "Say So" was shot on location in New Orleans with director Nathan Corrona.

Morton packs up his things and attempts to drive away, only to return, suitcase in hand at JoJo's door.