He was credited with five tackles (four solo) but the Buccaneers were crushed by the Houston Texans 37-9 to fall to 4-5 on the season.
Haynesworth started even though he didn't practice with his new team until Thursday.
The 350-pound defensive tackle said Thursday he was motivated to leave behind two-plus disappointing seasons with Washington and New England and prove he can still be a productive player.
The 10th-year pro developed into one of the league's top defensive linemen during seven seasons with the Tennessee Titans, but has underperformed since rejecting an offer from Tampa Bay as a free agent in 2009 and signing a seven-year, $100 million deal with the Redskins.
New England obtained him in a July trade, but Haynesworth had little impact in a part-time role and lasted just eight games with the Patriots.
Coach Raheem Morris and general manager Mark Dominik believe Haynesworth still has the talent to excel in a 4-3 defensive scheme after struggling in Washington and New England.
Haynesworth is in the lineup Sunday against the Houston Texans, filling in for the injured Gerald McCoy. McCoy tore his right biceps last week and his backup, Frank Okam, is inactive with a sore calf.
Receiver Andre Johnson was inactive for the Texans with right hamstring injury that's sidelined him more than a month. Quarterback T.J. Yates, cornerback Sherrick McManis, safety Danieal Manning, guard Thomas Austin, tackle Andrew Gardner and tight end Garrett Graham were Houston's other inactives.
Information from The Associated Press contributed to this report.