The nine-time Pro Bowler's No. 58 was retired at Arrowhead Stadium on Sunday during halftime of the Chiefs' game against the Denver Broncos.
The Thomas family, his coach Marty Schottenheimer and several former teammates were there to see Thomas become the 10th Chiefs player to have his number retired. One of Thomas' daughters wept as she left the field after the ceremony.
Thomas is the franchise leader with 126½ sacks, including an NFL-record seven in one game. He died from injuries suffered in a car crash in 2000, not long after completing his 11th NFL season.
Thomas was inducted into the Pro Football Hall of Fame in August.