Allen will play for the 49ers in Sunday's game at Dallas after being acquired in a trade earlier this week, David Lombardi of The San Francisco Standard reports.
Allen could have a significant role immediately, joining an injury-riddled WR room, though Deebo Samuel (hamstring) has been cleared to play this Sunday. Mike Evans (Achilles) is out again, leaving Samuel, Allen, Demarcus Robinson and Jordan Watkins as the top healthy options at wide receiver. San Francisco coach Kyle Shanahan mentioned Wednesday that Allen still has some risk of being suspended at some point this season due to an August arrest for DUI while he was with the Colts, per 95.7 The Game.