[2] After graduation from high school in 1989, Painter enrolled at Purdue University and played point guard for the Boilermakers, starting for one season.

Immediately afterward, Painter signed a six-year deal as head coach of the Purdue Boilermakers, where he would spend a year as a coach-in-waiting until Gene Keady's retirement at the end of the season.

He played four seasons as a Boilermakers point guard under head coach Gene Keady and assistants Bruce Weber and Steve Lavin.

Painter then moved to Division I as an assistant coach at Eastern Illinois of the Ohio Valley Conference, where he also received his master's degree.

Leading the Salukis to a 25–5 record and a berth in the 2004 NCAA tournament, the team was ranked as high as #15 in the nation by the AP poll during the season.

In his first season in that role, despite the absences of injured starters, David Teague and Carl Landry, and only playing with seven scholarship players, they finished with a 9-19 record.

Painter's first Purdue squad as a head coach came up with wins against eventual NCAA Tournament qualifier Wisconsin and #23 Michigan.

Both power forward Carl Landry and shooting guard David Teague returned to the lineup after injuries, combining an average of about 34 points and 15 rebounds per game.

Painter's Boilermakers finished the non-conference season with an 11-3 record, which included wins over previously unbeaten and top 25 schools Virginia and Missouri.

They received a 5th seed in the Big Ten tournament and were knocked out in the semifinals when they lost to a Greg Oden-led Ohio State team.

They had five returning starters from the prior season, including Chris Kramer, the conference's defensive player of the year and two all-conference selections in E'Twaun Moore and Robbie Hummel.

Near the end of the regular season, he was selected as one of ten candidates for the Henry Iba Award, which goes to the nation's best coach of the year.

After beating Washington in the second round, Purdue reached their first Sweet Sixteen in 9 years, eventually losing to Jim Calhoun's Hasheem Thabeet-led UConn.

He returned his entire regular starting five, including three all-conference selections in JaJuan Johnson, E'Twaun Moore, and Robbie Hummel.

Painter started his fifth season at Purdue with his team receiving a preseason 7th overall ranking by both the Associated Press and Coaches Polls, the program's highest in 22 years.

Coach Painter led his top ten ranked team to the 2009 Paradise Jam tournament championship against Bruce Pearl's #10 Tennessee, followed by the preseason close with a home win over #6 West Virginia and a 12-0 record against non-conference opponents.

Coming off the most wins in a four-year span in school history with 102 (2007–2010), Painter and his Boiler squad returned two All-American candidates (JaJuan Johnson, E'Twaun Moore), its primary point guard (Lewis Jackson), and an All-Conference freshman (Kelsey Barlow).

[8] These predictions came premature as fellow All-American candidate, Robbie Hummel, re-tore his ACL during practice, preventing him from playing his senior season.

Joining the sidelines was Painter's latest addition to his bench staff, Mike Jackson, a former Michigan assistant coach.

In preseason play, Painter's team began the season ranked as high as eighth in the nation and fell as low as 22nd following a loss to Richmond in the Chicago Invitational finals.

On November 11, Painter's squad opened the season beating Northern Illinois by 62 points, the program's highest win margin since 1911.

Closing the preseason with a 10–3 record and a 3–2 start in conference play, Purdue owned the fifth longest home winning streak in the nation at 27 before losing to Wisconsin.

In his 10th season as Purdue's head coach, Painter brought in three contributing freshman, including the tallest player in the program's history, 7'2" Isaac Haas.

Painter accomplished a first in his coaching career by landing a five-star recruit in 2015 Indiana Mr. Basketball Caleb Swanigan, who switched his commitment from Michigan State to Purdue.

During that time, the Boilers led the nation in scoring margin, points per game, three-point shooting, and was one of only two teams with a top 3 ranking in both offensive and defensive efficiency.

In the second round, they handedly defeated #6 seed Villanova, sending the defending champs home early after an 87–61 victory, and advancing to their third straight Sweet Sixteen in his tenure.

After a back and forth contest that included 17 lead changes and needed overtime to be decided, Purdue came out victorious, beating the Vols 99–94 to reach their first Elite Eight in nearly 20 years.

Virginia was able to come up with the offensive rebound however, and after chasing down the loose ball, Mamadi Diakite nailed a last second jumpshot at the buzzer to send the game to overtime.

The Boilers were once again looking towards the big dance, leading 75–74 with 43 seconds to go, but Virginia was able to hold Purdue scoreless the rest of overtime and prevailed 80–75, ending the Boilermakers' season with 26 wins and their first Elite Eight appearance since 2000.

On November 27, after winning the Maui Invitational, they made Big Ten history as the first team to be ranked number 1 in the AP Poll 3 consecutive seasons.