Before being hired by the Big Ten Network, Beilein served as the head coach of the Cleveland Cavaliers of the National Basketball Association (NBA).

[4] He has been recognized as conference coach of the year five times: in 1981 at Erie Community College, in 1988 at LeMoyne, in 1994 at Canisius, in 1998 at Richmond, and in 2014 at Michigan.

[14] His mother's cousins were the inspiration for Saving Private Ryan, and two of his uncles (Tom and Joe Niland) were lifelong basketball coaches in the Western New York area.

[18] Beilein was named the 1988 MCC Coach of the Year, when his team finished as co-conference champions with a 21–5 regular season record and number 14 national ranking.

[28] A Western New York native, he had grown up a Canisius basketball fan because his uncle, Joe Niland, had been a former player and coach there.

In his first two seasons at Canisius, Beilein turned a last place 1991–92 squad into a 1993–94 team that recorded the first undefeated home schedule (15–0) in the school's modern era.

[29] The team entered the 1994 MAAC tournament on a 15-game winning streak,[30] and Beilein earned Metro Atlantic Athletic Conference Coach of the Year.

[31] Beilein's number one seeded Canisius team lost in the second round semi-final contest against Loyola University and thus failed to make the 1994 NCAA tournament.

[41] A pair of subsequent wins enabled Canisius to earn a trip to the semifinals of the 1995 NIT at Madison Square Garden.

Beilein relied on a nucleus that included two freshmen and two sophomores after two returning starters were removed from the team for disciplinary reason during the 1998–99 season.

[64][65] Then with the CAA conference's automatic bid to the 2000 NCAA tournament at stake, Richmond lost to fourth seeded UNC Wilmington in the championship game.

[105] In the NCAA tournament, West Virginia beat Creighton 63–61 with a defensive stop and fast break dunk in the final five seconds.

[106][107] West Virginia then defeated the number two seed Wake Forest team led by Chris Paul in double overtime 111–105.

[111][112] In the elite eight round, they lost 93–85 in overtime to Rick Pitino's number four seeded Louisville, who were led by Taquan Dean and Larry O'Bannon.

During the 2005–06 season, West Virginia won its first eight Big East conference games and entered the top ten in the 2005–06 national rankings in February.

[144] In the semifinal contest against Mississippi State, they won 63–62 on a last-minute shot by Darris Nichols after recovering from a 14-point second-half deficit.

[145][146] The day before the championship game, Beilein was announced as one of three finalists (along with Kevin Stallings and Chris Lowery) for the Michigan Wolverines' head coaching job.

Beilein inherited a Big Ten Conference team that was in the final year of a scholarship reduction due to the involvement of former players in the Ed Martin scandal, in which NCAA rules had been violated.

With that win, Beilein had achieved a 20-win season at seven different schools, including four at the Division I level (Canisius, Richmond, West Virginia, Michigan).

[187][188] In the 2013 Final Four, the Wolverines defeated East region champion Syracuse, 61–56, to advance to the national championship game against Louisville, which they lost, 82–76.

[195][196] Then, the team won three in a row against top-10 ranked conference opponents including a road victory over 3rd-ranked Wisconsin[197] en route to a 10-game winning streak.

[199] He clinched his fourth career conference championship and second at Michigan on March 1 against Minnesota, and won the title outright three days later at Illinois.

[6][202] On March 11 Beilein was named District V (OH, IN, IL, MI, MN, WI) Coach of the Year by the United States Basketball Writers Association (USBWA).

In June 2017, Beilein's title was renamed as the David and Meredith Kaplan Men's Basketball Head Coach at Michigan.

On May 13, 2019, Beilein was named head coach of the Cleveland Cavaliers of the National Basketball Association (NBA), signing a five-year contract.

[238][239] Beilein was criticized for bringing his college game coaching style to the pros, including too much of an emphasis on fundamentals and an offense not suited to the NBA.

[248] Beilein modeled his offense from the Princeton system, which emphasizes constant motion, back-door cuts, picks on and off the ball, and precise shooting.

From this formation, Beilein's teams not only try to open up space for players to cut to the basket, but also are known for their high number of three-point attempts.

[253] The Beileins have three sons (Patrick, who played for his father at WVU and followed in his father's footsteps as the head basketball coach at Le Moyne; Mark, a former football player at Richmond and WVU grad who currently works for Alro Steel;[254][255] and Andrew, a Michigan grad who currently works for the Business Roundtable in Washington, D.C.[256]).

[263] According to 13.02.3, a contact includes any face-to-face encounter between a prospective student-athlete ... and an institutional staff member or athletics representative during which any dialogue occurs in excess of an exchange of a greeting.