The 32-year-old will earn the veteran's minimum of just over $1 million with the Bucs, a source told NFL Network's Ian Rapoport.
"He's very excited to play with established vets like Brady and Gronk in trying to win another championship," Rosenhaus said.
The Bucs have plenty of talent at wide receiver and tight end, but the unit's weakest link was arguably the running back position. Before McCoy's signing, sophomore Ronald Jones and rookie Ke'Shawn Vaughn topped the depth chart.
McCoy, who is entering his 12th NFL season, was a solid receiving back during his time with the Philadelphia Eagles and Buffalo Bills.
The veteran spent the 2019 season with the Kansas City Chiefs, earning his first Super Bowl title.
In 13 appearances, McCoy averaged 4.6 yards per carry (his best mark since a career-high 5.4 in 2016) and racked up 465 rushing yards and four touchdowns. He caught 28 passes for 181 yards and one score.