The deal was worth $55.5 million, according to local reports, and will put Jackson in a new uniform after he spent his first seven seasons with the San Diego Chargers.
A two-times Pro Bowl selection, Jackson is a 6-foot-5 target with three 1,000 receiving-yard seasons in his career.
His departure from the Chargers comes after he held out for most of the 2010 season because of a contract dispute but did make his way back to the field last season when he made 60 catches for nine touchdowns.
His arrival at Tampa Bay is expected to have a positive impact on the Buccaneers 24-year-old quarterback Josh Freeman.
The Buccaneers went 4-12 last season and fired head coach Raheem Morris.