Martin, the 31st overall selection in this year's draft, rushed for 1,299 yards and 16 touchdowns and had 28 receptions for another 255 yards and two touchdowns last season for the Broncos.
Over a four-year career at Boise State, Martin had 3,431 yards and 43 touchdowns rushing. He caught 67 passes for 715 yards and four touchdowns.
Alabama Safety Mark Barron, who Tampa Bay made the No. 7 overall pick in the draft, is the only player of the 2012 Buccaneers draft class unsigned.