Cain signed a contract with the Bills' practice squad Wednesday, Alec White of the team's official site reports.
Cain hasn't seen significant NFL regular-season action since 2019, although he's recorded a combined 49 receptions for 68 yards and five touchdowns with the Birmingham Stallions in the USFL and UFL the last two springs. Cain will have the opportunity to stick around in Buffalo for now after joining the team Aug. 13 and recording three catches for 28 yards during the preseason.