Seattle SuperSonics (1998–2005)

After retiring in 1998, McMillan stayed in Seattle as an assistant under Paul Westphal. He held this role until 2000 when the Sonics fired Westphal and made McMillan interim coach. Although the team missed the playoffs during his first year, he earned a winning record of 38–29 as interim head coach. He was hired as head coach for the 2001–02 campaign and led the club to the playoffs.^[7]

McMillan's Sonics had mediocre records the next two years, going 40–42 and 37–45. In the 2004–05 season, he led the team to 52–30 record in the regular season.^[7] The team advanced to the Western Conference semifinals, where they lost to the San Antonio Spurs.^[8]

Portland Trail Blazers (2005–2012)

After spending 19 years in Seattle as a player and coach, McMillan left Seattle on July 6, 2005, to become the head coach of the Portland Trail Blazers.^[9] He took over a team riddled with cap problems and off-the-court drama, but steadily calmed the waters in Portland. His hard-nosed coaching style earned him the nickname "Sarge."^[6] On December 5, 2009, McMillan ruptured his right Achilles tendon while scrimmaging with the Trail Blazers during practice.^[10] He coached much of the season in a protective boot after surgery and led the team to 50 wins in spite of a historic number of injuries to his key players. McMillan coached the Blazers until March 15, 2012.^[11]

Indiana Pacers (2013–2020)

On July 1, 2013, McMillan was hired by the Indiana Pacers as an assistant coach for the 2013–14 season.^[12] He replaced Brian Shaw, who accepted the head coaching position with the Denver Nuggets.^[13] In May 2016, after former head coach Frank Vogel's contract was not extended, McMillan was promoted to replace Vogel as the Pacers' coach.^[14] In McMillan's first year as head coach, the team experienced turmoil surrounding the displeasure and eventual departure of All-Star Paul George, who was traded to the Oklahoma City Thunder in June 2017. Despite this drama, the Pacers made the playoffs in all four of McMillan's seasons with the team, including three straight years without George. This was due largely to the emergence of the two players for whom he was traded, Victor Oladipo, who won the league's award for Most Improved Player in 2017 and was named to his first All-Star team in 2018, and Domantas Sabonis, who would also become an All-Star two years later in 2019. On August 12, 2020, Indiana announced that they had extended McMillan's contract. However, he was then fired a mere two weeks later, on August 26, 2020, after the Pacers were swept in the first round of the playoffs for the second year in a row, the fourth first round exit and third first round sweep in four playoff appearances under McMillan.^[15]

Atlanta Hawks (2020–2023)

On November 11, 2020, the Atlanta Hawks hired McMillan as an assistant coach under Lloyd Pierce.^[16] On March 1, 2021, McMillan was named interim head coach after the firing of Pierce.^[17][18] Following McMillan's promotion, Atlanta promptly went on an eight-game winning streak, begun with a victory over the defending Eastern Conference champion Miami Heat on March 2, 2021, and capped off by a win over the defending NBA champion Los Angeles Lakers on March 20, 2021.^[19] The Hawks finished the season 27-11 under McMillan's leadership,^[20] ending a four-year playoff drought and earning the fifth seed in the Eastern Conference. Atlanta's success continued on into the playoffs. They beat the fourth-seeded New York Knicks in five games, and continued their improbable run by upsetting the top-seeded Philadelphia 76ers in a hard-fought seven-game series. With that series win, the Hawks made it to the Eastern Conference finals, only the second time in 54 years they have advanced past the second round. There they faced the third-seeded Milwaukee Bucks, led by two-time league MVP Giannis Antetokounmpo. McMillan led the Hawks to their first ever win in the conference finals, defeating the Milwaukee Bucks 116–113 in Game 1. The Hawks would lose the series in six games.^[21]

On July 5, 2021, McMillan and the Hawks agreed in principle to drop the "interim" tag from his title and make him the franchise's 14th head coach since the team moved to Atlanta, with a four-year contract. General manager Travis Schlenk said that while the language of the contract was still being drawn up, "I'm excited he's going to be our head coach going forward."^[22] The deal was formally announced on July 7, with Schlenk praising the "incredible job" McMillan had done after taking over the team in mid-season.^[23]

On February 21, 2023, the Hawks fired McMillan after the team posted a 29–30 record going into the All-Star break.^[24][25]

NBA