Gradkowski, a sixth-round pick by the Buccaneers in 2005, was placed on waivers on May 31. With six quarterbacks on the roster and a plan of taking five from the position into training camp, Tampa Bay deemed Gradkowksi expendable.
Gradkowski joins a group of Rams quarterbacks that includes starter Marc Bulger, veteran backup Trent Green and second-year player Brock Berlin.
Gradkowski played sparingly in four games last season, completing 13-of-24 passes for 130 yards and one interception. He saw significant playing time as a rookie in 2006 as an injury replacement for Chris Simms, starting 11 of his 13 games and completing 54.0 percent of his passes for 1,661 yards, nine touchdowns and nine interceptions.