In 2003 New England Patriots drafted Ty Warren in the first round (13th pick overall) of the 2003 NFL draft. In his rookie season with the Patriots he play in all of the regular season and postseason games and started 4 of them. He recorded his first NFL sack on October 19, 2003 in an overtime victory over the Miami Dolphins. Warren ended 2003 with 33 total tackles and 1 sack.
In 2004, Warren moved from backup defensive end to full-time starter at the position. He started all 16 of the Patriots regular season games and had 48 tackles and 3.5 sacks. He was a key contributor to the Patriots defense that shut down Indianapolis Colts record smashing offense in a 21-3 Patriots Divisional Playoff victory and in the Patriots 24-21 victory over the Philadelphia Eagles in Super Bowl XXXIX he had 1 tackle. In 2005, he became a major run stuffer and as he had a total of 68 tackles and 1.5 sack. His sack and a half both came on a Week 11 game on Monday Night Football. He also had a fumble recovery in the game. He started all 16 games for the Patriots that year.
In 2006, Warren was considered by many to be worthy of a spot on the AFC Pro Bowl team. His performance backed up his candidacy for the award. In 2006 he set career highs in both tackles (84), and sacks(7.5) and he also batted down 4 passes. In the first week of the regular season vs the Buffalo Bills he scored the winning points for the Patriots when he sacked Bills quarterback JP Losman in the endzone for a safety. The Patriots won the game by the score of 19-17 with his safety (worth 2 points) being the last points scored in the game... The Boston Herald named Warren as the Patriots defensive player of the year Warren is expected to start at defensive end for the Patriots in 2007.