The deal was announced Monday night.
Jensen spent last season with Triple-A New Orleans, hitting .260 with 27 homers and 92 RBIs in 133 games. He was tied for fourth in the Pacific Coast League in homers, and his RBI total ranked second.
In 577 minor league games, the 26-year-old Jensen has played right and left field, first base and been the designated hitter.
Jensen, a 6-foot-3, 250-pounder from Walnut Creek, California, was originally drafted by the Marlins in the 12th round of the 2009 amateur draft after he attended St. Mary's Preparatory School in Michigan.