Ward had been scheduled to make $4.5 million with the Denver Broncos in 2017 but was released Saturday after three seasons with the team.
After he was released, he thanked the Broncos and their fans and said he "was looking forward to my next chapter."
The Bucs upgraded their safety position this offseason by signing J.J. Wilcox from the Dallas Cowboys and selecting Texas A&M's Justin Evans with a second-round draft pick. Neither unseated the Bucs' two returning players at the position -- Chris Conte and Keith Tandy, who were expected to start the season opener against the Miami Dolphins.
Ward, 30, has a history with Bucs director of player personnel John Spytek, who was with the Browns' front office when Cleveland drafted Ward in 2010; Spytek also worked as a scout for the Broncos from 2013 to 2015 before joining the Bucs.
In 14 games last season, Ward registered 87 combined tackles (69 solo), eight pass breakups, three forced fumbles, an interception and a sack. In the Broncos' Super Bowl 50 win over the Carolina Panthers, Ward had an interception and a fumble recovery.
In training camp this year, he dealt with hamstring issues that kept him out of the preseason. The Broncos had also drafted two safeties in 2016 -- Justin Simmons, who did not miss a single tackle last season, according to Pro Football Focus, and Will Parks.