At Graford High School, Gillispie played point guard for the basketball team and was a standout athlete in his graduating class of 20 students.

[4] Gillispie was hired as the head coach of the men's basketball team at the University of Texas at El Paso (UTEP) in 2002.

[4] After two years at UTEP, Gillispie was approached to interview for the head coach position at Texas A&M University, vacant after the forced resignation of Melvin Watkins, whose team had gone 7–21 and failed to win a Big 12 Conference game in the 2003–04 season.

[2] Athletic Director Bill Byrne needed to revitalize the program, which had only one winning season in the previous eleven years,[6] and desired a new head coach with the ability to "recruit the heck out of Texas".

[2] Gillispie agreed to take the job only after he was sure that the predominantly football-focused school was actually committed to winning,[2] becoming the first native Texan to be the head basketball coach at Texas A&M since J.

[3] Gillispie asked for a budget large enough to allow them to play confidence-building non-conference schedules, rarely venturing out of Reed Arena in the first two seasons.

[4] With the best first-season record of any head basketball coach in Texas A&M history, the Aggies had the most season wins since the 1979–80 team had won 26 games.

[6] Although the Aggies lost Antoine Wright to the NBA draft following the 2004–05 season, the team did not suffer the predicted drop-off,[4] and actually broke a streak of twenty-five years without being ranked in the poll.

Less than forty-eight hours later the Aggies defeated their archrivals, the #25 ranked Texas Longhorns, marking their 21st straight win at home.

[12] On April 5, 2007, University of Kentucky athletic director Mitch Barnhart was given permission by Texas A&M to speak with Gillispie about the program's basketball coach opening, vacated by Tubby Smith.

[13] He drew criticism for the way he left Texas A&M by having alerted the Aggie players of his decision to take the Kentucky job via text message, while en route to the introductory press conference in Lexington.

[14] On April 6, 2007, Gillispie was formally announced as the new head coach of the University of Kentucky by UK athletic director Mitch Barnhart.

He fielded questions from the media during a press conference held at UK's new practice facility, the Joe Craft Center.

Wildcat fans packed Rupp Arena for Big Blue Madness (the first practice of the season and the program's major publicity event) to catch a glimpse of their new coach in action.

Patterson had previously been recruited by the Duke Blue Devils, Florida Gators, and Kentucky Wildcats (by former coach Tubby Smith) before signing with Gillispie.

[21] On November 14, 2008, Gillispie's Kentucky team opened the 2008–09 season with another loss at home, this time to the Virginia Military Institute (VMI) Keydets, by a score of 111–103.

However, on November 30, 2008, Gillispie led Kentucky to a 54–43 come from behind victory over the West Virginia Mountaineers to win the Findlay Toyota Las Vegas Invitational championship.

After a 5–0 start in the SEC conference schedule, however, Gillispie's team dropped three straight games to the Ole Miss Rebels, South Carolina Gamecocks and Mississippi State Bulldogs, with the latter two losses coming at home.

Nick Calathes had an opportunity to tie the game after being fouled with 0.6 seconds left by Kevin Galloway, but missed all three free throws (the last intentional) to seal the Wildcats' win.

Although Gillispie continued to take the blame for the Wildcats' woes, he was also a victim of some of his youthful and inexperienced recruits' underperformance and the lack of consistent play at the point guard position.

Gillispie continued to publicly encourage his players and praise their work ethic despite the team's inconsistent play during the 2008–09 season.

[22][23] Kentucky missed the NCAA Tournament for the first time since 1991, and received a 4th seed in the NIT, defeating UNLV and Creighton in the opening and second rounds before losing to the Notre Dame Fighting Irish in the quarterfinals.

[27] On May 27, 2009, Gillispie filed a lawsuit against the University of Kentucky Athletic Association for breach of contract and fraud stemming from the firing.

[28] Gillispie was seeking $6 million, the amount he claimed the university owed him on the remaining years on the deal, punitive damages, attorney fees, and a jury trial.

[28] The next day, the university filed a countersuit against Gillispie in Franklin Circuit Court in Frankfort, Kentucky's state capital.

Fifteen players departed prematurely in the year after Gillispie arrived, a very high number for a college basketball program in a major conference.

[39] On December 7, 2016, Gillispie announced his immediate retirement from coaching, citing severe health issues related to his blood pressure.

With the sheer number of hours he spent working, Gillispie often did not have time to even shop for groceries, once going as long as six months without any food in his refrigerator.

The officers who were at the scene smelled a strong odor of alcohol, describing Gillispie's eyes as being red and glassy, with his speech slurred.

He was arrested again in 2003 in his first year at the University of Texas at El Paso on suspicion of drunken driving, although it was later dismissed based on a lack of evidence.