As a sophomore in 1994, he played for the John Tyler High School Lions team under coach Allen Wilson, which went 16–0 and won the 5A Division II state championship in Texas.
Recruited by virtually every school in the nation, Warren decided to play for the Florida State Seminoles under Coach Bobby Bowden.
In his true freshman season Warren played in 11 of 12 games, appearing as back-up defensive end behind Tony Bryant and on special teams, and recorded 16 tackles (eight solo) on the year.
As a sophomore, Warren moved in the Florida State defensive two-deep and saw playing time as back-up to Roland Seymour.
He finished the season with 32 total tackles, 17 solo stops, and two sacks, while tying for the team lead with three fumbles caused and led all defensive linemen with four passes broken up.