Marinelli went to the Tampa Bay Buccaneers in 1996 and was the defensive line coach for six seasons under head coach Tony Dungy. In the latter four seasons he also served as assistant head coach, winning a Super Bowl in 2003. He was known for his structured approach and his commitment for trying to get the most out of his players. There he worked to develop linemen such as Warren Sapp and Simeon Rice into Hall of Fame caliber players. During Marinelli's tenure in Tampa Bay, the Buccaneers earned more sacks than any other franchise.