One of nine children born to parents, Kevin and Vera, who divorced when he was thirteen years old, Mobley lived with his father until the age of sixteen.
Mobley made the starting lineup as a freshman and recorded nine tackles and a sack in his first college game, and earned an honorable mention on the All-American team as a sophomore.
Mobley's college career came to a sudden halt in 1993, however, when coach Barry Fetterman was fired as a result of an NCAA investigation into academic violations at the school.
Mobley suffered a bruised spinal column during the 2003 season after colliding with his teammate Kelly Herndon in a game against the Baltimore Ravens.
The deflection sealed a 31–24 victory for the Broncos and ended the NFC's run of 13 straight wins over the AFC in Super Bowl competition.