Following high school, Faulk attended Louisiana State University, where he immediately became the starting running back for LSU's football team as a true freshman in 1995. In 1996, Faulk was voted to the College Football All-America Team by the Associated Press. Faulk finished his LSU career with 4,557 yards rushing in 41 games.
Faulk was selected by the New England Patriots in the second round (46th overall) of the 1999 NFL Draft. In 2000, Faulk shared a starting role with rookie J. R. Redmond, with Faulk starting 9 of 16 games played. He led the team with 570 yards rushing on 164 carries with four rushing touchdowns. He added 51 catches for 465 yards and one touchdown. He was also active on special teams, leading the team with 38 kickoff returns for 816 yards while also returning six punts for 58 yards.
On December 22, 2001 against the Miami Dolphins, Faulk completed a 23-yard pass to quarterback Tom Brady, his first career pass completion. Faulk and the Patriots would go on to win Super Bowl XXXVI over the St. Louis Rams.
In the 2002 season, he became the first player in franchise history and the only NFL player in the 2002 season to record multiple touchdowns in three different categories: rushing, receiving, and kick returns. In 2003, Faulk finished the season with career highs of 178 carries for 638 yards as well as 48 receptions for 440 yards. He added 10 kickoff returns for 207 yards and 5 punts returns for 66 yards. Faulk also set a career high in fumbles in 2003, with four.
Faulk and the Patriots finished the season with a league-best 14–2 record, advancing to Super Bowl XXXVIII. Faulk helped the Patriots to a 32–29 victory in the game over the Carolina Panthers with 42 yards rushing and 19 yards receiving. His longest plays were a 23-yard run in the fourth quarter and a two-point conversion score with 2:51 left in the fourth quarter; the direct snap run was the only score by Faulk in 2003.
Faulk played in the first three games of 2005 before suffering a foot injury and not returning until Week 13 in December. In eight games played (two starts), Faulk had 145 yards rushing on 51 carries and 29 catches for 260 yards. He also returned 4 kickoffs for 81 yards.
During the 2008 season, Faulk finished with 83 carries for 507 yards and three touchdowns, as well as a career high 58 receptions for 486 yards and three touchdowns. On special teams, he added 2 kickoff returns for 36 yards and 10 punt returns for 132 yards.
