Dunn was drafted in the first round by Tampa Bay in 1997 and was the team's feature back until he left for Atlanta in 2002. He remains third on the team's all-time rushing list with 4,200 yards. The Bucs initially let Dunn go because of concerns about salary-cap space and his durability.
But Dunn proved those doubts wrong in Atlanta, rushing for 5,979 yards in the past six seasons. Dunn was released by Atlanta last week after the Falcons brought in free agent Michael Turner from San Diego.
Dunn is 33 and one of only 22 players in NFL history to rush for more than 10,000 yards. He isn't expected to be a feature back in this stint with the Bucs, but he could share time in a backfield that may have to start the season without Carnell Williams, who is coming off a major knee injury.
Pat Yasinskas covers the NFL for ESPN.com.