Haney (31-0, 15 KOs) dominated Prograis (29-2, 24 KOs) throughout the fight, dropping him once in Round 3.
Haney relinquished his 135-pound belts in November and plans to continue his career at junior welterweight. He unified the 140-pound division by defeating George Kambosos Jr. in June 2022 and defended the belts twice, in a rematch against Kambosos in October 2022 and against Vasiliy Lomachenko last May.
Also on Saturday night, Robeisy Ramirez lost to Rafael Espinoza by majority decision in a WBO featherweight title in Pembroke Pines, Florida.
Ramirez, who entered the fight as a 11-to-1 favorite to retain the title, put on a great fight -- one of the judges scored the fight a draw -- but it wasn't enough to get the win as Espinoza outworked Ramirez to claim the 126-pound belt.