Clayborn's deal is for one year and is worth a maximum value of $4.5 million, a league source said.
Clayborn (6-foot-3, 280 pounds), a former first-round pick of the Buccaneers in 2011, enjoyed a strong start to his career, with 7.5 sacks in his rookie season. He also had 5.5 sacks during his third year. But in 2014, Clayborn tore his biceps in the season opener and missed the rest of the season. He also missed 13 games in 2012 with a knee injury.
Clayborn, who turns 27 in July, also has battled Erb's palsy, a condition that caused nerve damage to his right shoulder and arm when the doctors pulled him too hard through the birth canal. It hasn't prevented him from succeeding on the football field.
Clayborn has a familiarity with the Atlanta coaching staff. He was drafted by Falcons assistant head coach Raheem Morris when Morris was the head coach of the Buccaneers. He also played under defensive line coach Bryan Cox when Cox was in Tampa.
Already signed by the Falcons were linebackers Brooks Reed and Justin Durant along with guard Mike Person. Reed, known more as a run-stopper, could help contribute to the pass rush in certain situations.
The Falcons, who finished second to last in sacks per pass play the last two seasons and last in third down defense a year ago, are looking to develop a consistent pass rush under new coach Dan Quinn.
The team is expected to draft a pass-rusher in the first round of this year's draft with the eighth-overall pick. The elite group of rushers includes Florida's Dante Fowler Jr., Nebraska's Randy Gregory, Clemson's Vic Beasley and Missouri's Shane Ray. Beasley is scheduled to visit the Falcons on March 30 while Ray has a visit scheduled for April 10.
Schofield played under Quinn the last two seasons when Quinn was the defensive coordinator for the Seahawks.