Bills coach Doug Marrone made the announcement after practice Wednesday night.
Kolb, who is competing with rookie EJ Manuel for the starting quarterback job, did not play in Buffalo's first preseason game because of a left knee injury.
Marrone said the decision was not a reflection of Manuel, who played well against the Indianapolis Colts on Sunday, and more about the competition at quarterback.
"Kevin probably would have started the first game if he wasn't injured or hurt, and EJ would have come in and then EJ would have started this game," Marrone said. "But because of injury, obviously EJ started and I'm going to get Kevin his start. You can't call it a competition and then all of the sudden not have the quarterbacks getting those starts."
Kolb twisted his knee when he slipped on a wet rubber mat during practice. He signed with the Bills after two injury-filled seasons with the Arizona Cardinals.
Kolb participated in team drills for the first time in over a week on Monday but took a big step forward Tuesday. On Tuesday, Kolb moved well in the pocket and did not appear to be hampered by the knee injury.
"(Tuesday) was a big day for me," Kolb said. "I felt my feet get back underneath me and was able to push the ball down the field a couple of times and I was happy with it."
Bills rookie linebacker Kiko Alonso will likely miss Friday's game as he makes his way back from a shoulder injury. Alonso has been cleared by doctors to return to the field but Marrone said he plans on resting him for a couple days.
Wide receivers Stevie Johnson (hamstring) and Brad Smith (undisclosed) returned to practice on a limited basis Wednesday night. The Bills are hoping that Johnson, Buffalo's top receiver, will return on a full-time basis next week before the team's third preseason game.
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