As a head coach in the National Basketball Association (NBA) with the Los Angeles Lakers, he introduced an up-tempo style of play that became known as Showtime.

He played three seasons for the Hawks, who were also coached by Dr. Jack Ramsay, and led the team to the Big 5's inaugural title and the school's first ever postseason in the 1956 National Invitation Tournament (NIT).

[3] He was also named the Eastern Coach of the Year by Philadelphia sportswriters for his 1973–74 season when the Hawks, predicted to have a poor year after graduating Mike Bantom to the NBA and Pat McFarland to the American Basketball Association (ABA), had a stellar season again winning their conference and qualifying for postseason play.

[6][7] However, he was fired after a first-round loss in the 1974 NCAA Division I basketball tournament, and his dismissal prompted a demonstration by over 500 students.

Owner Jerry Buss, who had recently acquired the team, wanted games to be entertaining, and hired the coach to install a running offense.

[8][9] McKinney had 6-foot-9-inch (2.06 m) rookie Magic Johnson, who some thought should play forward, be a point guard, even though incumbent Norm Nixon was already one of the best in the league.

McKinney was soon hired as the head coach of the Kansas City Kings, but resigned from the position on November 18, 1984, after the team started with a 1–8 record in the 1984–85 season.

[21] He left coaching for good afterwards, citing ongoing issues with his memory, plus no longer feeling passionate about the profession.

He worked as a sales representative for a major sporting goods company, while also filling in at times as a color analyst for the Philadelphia 76ers broadcasts.

[2] McKinney was portrayed by Tracy Letts in the HBO documentary series Winning Time: The Rise of the Lakers Dynasty.