Winston, who suffered an AC joint sprain in his right throwing shoulder in last Sunday's 38-33 loss at Arizona, took every rep with the first-team offense Friday - the first day he had thrown passes since the injury.
"Jameis threw the ball well today. He threw it well," head coach Dirk Koetter said. "He'll be our starter. Jameis is our starter. He'll be out there."
Winston has not missed a start in 37 games in the NFL and has thrown all but 11 passes for the Bucs during that stretch.
Backup Ryan Fitzpatrick, who passed for 290 yards off the bench at Arizona, had taken all the first-team reps Wednesday and Thursday.
In other Bucs injury news, middle linebacker Kwon Alexander will make his first start Sunday at Buffalo since aggravating a hamstring injury in the season opener against Chicago.
Defensive end Robert Ayers, who was limited in practice Thursday with a knee injury, practiced on Friday.