Mikan received his undergraduate and legal education at DePaul University in Chicago, where Coach Ray Meyer transformed him from an awkward player into a hook-shooting offensive force. After a brief period with the Chicago American Gears (1946–47) of the professional National Basketball League (NBL), he joined the Minneapolis Lakers (1947–54 and 1955–56; now the Los Angeles Lakers), a team that was successively in the NBL, the Basketball Association of America, and, from 1949, the National Basketball Association. In nine seasons he scored 11,764 points in 520 regular games for an average of 22.6 points a game, and he scored 2,141 points in 91 championship games for a 23.5-point average. With Mikan at centre, the Lakers won six championships from 1947–48 through 1953–54 (1950–51 season excepted). After retiring in 1956, he coached the Lakers for part of the 1957–58 season.

In a era when the professional game was known for its rough play, the lanky and nearsighted Mikan, wearing thick protective goggles, hardly looked the part of a basketball star. However, despite numerous broken bones and countless cuts and bruises, Mikan thrived in the sport and handed out just as much punishment to his opponents.

When the professional American Basketball Association (ABA) was founded on Feb. 2, 1967, Mikan was named its commissioner (chief executive). He resigned on July 14, 1969, because the ABA office was to be moved to New York City from Minneapolis, where he was a successful lawyer and businessman. Mikan was inducted into the Basketball Hall of Fame in 1959.