The Bills needed a punter with Matt Araiza unavailable at the 11th hour.
Barkley has punted twice so far with kicks of 33 and 53 yards and one downed inside the 20.
Buffalo benched Araiza after it became public that a 17-year-old girl accused him of rape last year. He traveled with the team to Carolina.
The Bills drafted Araiza in the sixth round this spring.