Langer's seven-under 65 overcame the three-stroke deficit he started the day with.
His 7-under 65 gave him a 16-under 200 for the tournament, one shot better than Andy Bean.
Standing about 3 feet off the back fringe, Langer put the ball on the edge of the green and watched it roll about 15 feet into the hole. Langer turned and pointed to the crowd with both arms raised when the ball dropped in the hole for his fourth win of the season.
Scott Hoch (66) finished two shots back. Tom Kite shot his second 67 at the TPC Twin Cities to finish fourth. Nick Price, the leader after round two, shot a 1-under 71 to finish five back.