Gailey has previously served as the head coach of the Dallas Cowboys, Georgia Tech Yellow Jackets, and Buffalo Bills from 1998 to 2012.
In a coaching career spanning 46 years, Gailey began his NFL career as part of Dan Reeves' coaching staff on the Denver Broncos from 1985 to 1990, appearing in Super Bowls XXI, XXII, and XXIV with the Broncos.
In 2020, Gailey came out of retirement to again serve as the offensive coordinator for the Miami Dolphins, where he would last for only a season before resigning on January 6, 2021.
In his second season at the helm in 1984, he led his #3-ranked Trojans to a 12–1 record en route to the NCAA Division II national championship, defeating #1-ranked North Dakota State, 18–17 to win the title.
[7] Gailey moved to the NFL the next year, when the Denver Broncos signed him as an offensive assistant and special teams coach.
After a one-year stint as head coach at Samford University, he returned to the NFL with the Pittsburgh Steelers.
On February 13, 1998, Gailey was hired to take over a struggling Dallas Cowboys squad (as operated by Jerry Jones), one that had faltered under Barry Switzer during his last season.
Other candidates considered in the course of five weeks were George Seifert, Sherman Lewis, and Terry Donahue, with the latter being the closest to being hired before disagreeing with Jones about contract language that opened the door for Gailey.
This would come back to haunt them when they played the Arizona Cardinals, who happened to squeak into the playoffs as a Wild Card team despite losing to their division rival twice.
[15] Gailey's name was mentioned for both the Pittsburgh Steelers and Miami Dolphins head-coaching jobs following the 2006 season, two teams for which he was offensive coordinator.
[17] After a 7–5 2007 regular season and losing to the Georgia Bulldogs football team for the sixth straight year, it was announced on November 26, 2007, that Gailey had been dismissed and his $1 million/year contract bought out.
[23] He was demoted after three pre-season games in 2009 and relieved of play-calling duties by head coach Todd Haley.
[29] Gailey was named offensive coordinator by the New York Jets on January 20, 2015, under new head coach Todd Bowles.
[32] Following the 2016 season in which the Jets ranked near the bottom of the league in offense and finished 5–11, Gailey retired on January 3, 2017.