The three-time Pro Bowl selection signed Monday with the Bucs, who needed to bolster their running game because Carnell "Cadillac" Williams missed most of last season with a knee injury. There are also lingering questions about when Williams will be able to play again.
NFL Network's Adam Schefter reports it's a two-year, $6 million contract, including $2 million in guaranteed money and $3 million in the first year of the deal.
The 33-year-old played the first five seasons of his career with Tampa Bay, establishing himself as one of the league's top all-around backs. He was integral, along with Derrick Brooks, Warren Sapp, John Lynch and Mike Alstott, in transforming the Bucs from perennial losers to a championship team.
He spent the past six seasons with Atlanta, leaving the Bucs two months after former coach Tony Dungy was fired -- in part -- for not being able to get Tampa Bay to the Super Bowl.
Dungy's replacement, Jon Gruden, made a pitch to retain Dunn -- thought to be an ideal fit for the coach's version of the West Coast offense -- but a tight salary-cap situation prevented the Bucs from paying what the Falcons could offer in free agency.
Tampa Bay, which reached the NFC Championship Game with Dunn in 1999, won its only NFL title the year he left. The Bucs have since missed the playoffs three of five seasons.
Dunn flourished in Atlanta, becoming the franchise's third-leading rusher with 5,979 rushing yards. Last season, he became the 22nd player in NFL history to surpass 10,000 yards rushing.
He still ranks third on the Buccaneers' career rushing list with 4,200 rushing yards, and overall has 463 career receptions for 4,009 yards with 15 receiving touchdowns.
The Falcons released Dunn last week, two days after signing free agent running back Michael Turner, reportedly for $34.5 million with about $15 million guaranteed. He had three straight 1,000-yard seasons 2004-06, but only rushed for 720 yards in 2007 with the Falcons reeling from Michael Vick's dogfighting case.
Dunn, nearly as wellknown for his charitable work as his accomplishments on the field, has maintained a home in Tampa throughout his career. With the Bucs' running back situation, speculation about a possible return began as soon as Atlanta cut him.
Williams, the NFL's offensive rookie of the year in 2005, tore the patellar tendon in his right knee last September and missed the final 12 games of the season. The Bucs have had little to say about his status, except that he faces a tough rehabilitation.
Earlier Monday, the Bucs signed free-agent tight end Ben Troupe and wide receiver Antonio Bryant. Troupe played for the Tennessee Titans the past four seasons, starting 29 games. Bryant was a second-round draft pick by the Dallas Cowboys in 2002 then moved to the Cleveland Browns in 2004 and San Francisco 49ers in 2006.
Copyright 2008 by The Associated Press