A 6'11" power forward/center born in Tylertown, Mississippi and from Dillard University, he played in 13 National Basketball Association (NBA) seasons (1972–1983; 1984–1986) as a member of the Golden State Warriors, the Buffalo Braves, the New Jersey Nets, the San Antonio Spurs, the Atlanta Hawks, and the Seattle SuperSonics.

Johnson was a key reserve on the Warriors team that won the NBA Championship in 1975, and he grabbed 5,887 rebounds in his career.

[1][2] In 1981–82, Johnson started 62 games for the Spurs, helping them win the Midwest Division championship and reach the Western Conference finals.

After San Antonio was swept by the eventual champion Los Angeles Lakers in a series in which Johnson was badly outplayed by Kareem Abdul-Jabbar, Spurs coach Stan Albeck determined the team was seriously deficient in the low post.

Albeck sought a premier center, and got it by trading for Chicago Bulls All-Star Artis Gilmore, signaling the end of Johnson's time in San Antonio.