Fairley was born in Mobile, Alabama. He attended Williamson High School in Mobile, where he was a two-way lineman and also lettered in basketball. Regarded as a three-star prospect, he was projected as an offensive guard. He committed to Auburn, but could not qualify academically.
Fairley transferred to Auburn University, where he played for the Auburn Tigers football team in 2009 and 2010. He finished the 2009 season with two starts in 13 games and recorded 28 tackles. Surprisingly quick for his size, his tendency to be flamboyant following a successful play placed him as a person of concern for officials. In 2010, he became the 2nd player from Auburn to win the Lombardi Award. He was coached by Lombardi winner and former Auburn player Tracy Rocker, and became the first player to win the Lombardi and be coached by a winner of the award.
During the 2011 BCS National Championship Game against the Oregon Ducks, Fairley had five tackles, a sack and a forced fumble. Three of his tackles were made behind the line of scrimmage. Fairley was selected as the defensive player of the game award.
Only four days after the 2011 BCS National Championship Game, Fairley decided to forgo his final year of eligibility, entering the 2011 NFL Draft. He was initially projected to be the first pick in the draft. His measurements at the combine showed him to be 6 feet 3 7/8 inches tall and 291 pounds, somewhat less than his listing of 6-5 and 300 pounds at Auburn. After the combine, he was projected in the 8-12 range. Fairley was drafted by the Detroit Lions in the first round as the 13th pick overall.
Since entering the NFL, Fairley has had a number of run-ins with the law. On April 3, 2012, Fairley was arrested in Mobile, Alabama for marijuana possession. The charges were dismissed in December 2012.
On May 27, 2012, Fairley was arrested by Alabama State Troopers for driving under the influence and attempting to elude police. He was also ticketed for reckless driving, having an open container of alcohol in the vehicle and no proof of insurance.