Terms were not disclosed.
Campbell, 27, acquired from Cleveland in February, has played in all
eight games this season and ranks fourth on the team with 23 receptions for 197 yards.
He spent his first three seasons with the Browns, and has 69 receptions for 587 yards and four touchdowns in 54 games.
In Buffalo, Campbell replaced Jay Riemersma, who signed with the Pittsburgh Steelers.