Financial terms of the four-year deal were not disclosed.
Rainey (5-feet-8, 178 pounds) started 19 of 52 games at the University of Florida, splitting his time between slot receiver and tail back.
He finished his Gators career ranked ninth in school history with 2,464 yards rushing on 396 carries -- a 6.2 yard average. He scored 21 career touchdowns -- 13 rushing, six receiving and two on punt returns. He is the only Gator to record a rushing, receiving and return touchdown in the same game. He also blocked six punts in his career -- a Southeastern Conference record.