Warren attended the University of Florida in Gainesville, Florida, where he played for coach Steve Spurrier's Florida Gators football team from 1998 to 2000. As a junior team captain in 2000, Warren posted 76 tackles and 4.5 quarterback sacks at defensive tackle and was a second-team All-Southeastern Conference selection and a second-team All-American. He finished his three-season career as a Gator with 159 tackles, 9.5 sacks, and 30 tackles for a loss in 35 games and 22 starts.
Professional career
Cleveland Browns
Warren was drafted by the Cleveland Browns with the third overall selection in the 2001 NFL Draft. He played in 15 games as a rookie in 2001, all starts, and finished with 83 tackles and five sacks. In 2002, Warren started all 16 games, recording 56 tackles, two sacks, and two forced fumbles. He started 15 games for the Browns in 2003, picking up 70 tackles and a career-high 5.5 sacks. In his final season in Cleveland, 2004, Warren played in and started 13 games, missing three to injury, and finished with 38 tackles and four sacks.
Denver Broncos
In March 2005, Warren was traded to the Denver Broncos for a fourth-round pick in the 2005 NFL Draft. In addition to Warren, the Broncos also acquired defensive linemen Michael Myers, Ebenezer Ekuban, and Courtney Brown from the Browns, leading some to dub the new Broncos defensive line the "Browncos." Warren finished the 2005 season with 42 tackles and three sacks in 16 starts. In 2006, Warren started 15 games and recorded 30 tackles and 2.5 sacks on the season.
Oakland Raiders
In August 2007, during the preseason, Warren was traded by the Broncos to the Oakland Raiders in exchange for a conditional fifth-round draft pick in the 2008 NFL Draft. In 2007, Warren played in 12 games for the Raiders, posting 22 tackles, four sacks, and one forced fumble. Warren started all 16 games in the 2008 season, finishing with 39 tackles, four sacks, and one forced fumble. In his final season with the Raiders, 2009, Warren again started all 16 games and finished the year with 35 tackles and two sacks. He was released by the Raiders on March 11, 2010.
New England Patriots
On April 24, 2010, during the final day of the 2010 NFL Draft, Warren signed with the New England Patriots. Despite being a late free agent signing, Warren made the Patriots' roster and began the season as a starter at defensive end before moving to nose tackle in Week 6. After two games at nose tackle, Warren moved back to defensive end but did not start the team's Week 8 game against the Minnesota Vikings. He returned to the starting lineup in Week 12 against the Detroit Lions on Thanksgiving Day, and went on to start four of the team's final five games after Thanksgiving. Warren finished the regular season with 28 tackles and 3.5 sacks in 16 games. The Patriots re-signed him on August 8, 2011 after he had been a free agent for most of the offseason. During the 2011 season, he played in eleven games, all off the bench, and compiled a sack and 15 tackles. Afterward, he again became a free agent, but he re-signed with the Patriots on April 30, 2012. He was again released on August 26, 2012.
Gerard Warren is the second-cousin of Mahailya Reeves, the weightlifting sensation from Lake Butler, who, at only 15 years of age, recently set a Florida women's bench press record of 355 pounds.
