Farrior signed with the Pittsburgh Steelers in 2002, and he suited up at Inside Linebacker, the same position where he was an All-ACC Selection as a Cavalier.  Farrior would explode in 2004, finally going to the Pro Bowl and securing a spot on the First Team All-Pro squad, and he recorded a career-high 19 in Approximate Value.  The Linebacker was so good that he was second in Defensive MVP voting.

While 2004 was the greatest regular season of his career, it was far from the end of his career.  Farrior was a defensive anchor in the following season in their Super Bowl XL win.  Three years later, Farrior was a Pro Bowl Selection again, and once more, he was a significant component in a Super Bowl win by the Steelers.

Farrior played until 2011, retiring with the Steelers.  While wearing the black and yellow, Farrior had six 100-Tackle years with 1,085 total. Notably, he also managed to secure 30 Sacks.  The team would select Farrior for their Hall of Honor in 2020.