On March 24, 1958, Cokes began to box professionally, defeating Manuel Gonzalez, whom he would later fight for the world title, in a six-round decision.

He went 13–4 in his next seventeen fights, and, after losing in a ten-round decision to Eddie Pace at Los Angeles, California, on August 27, 1964, he announced his retirement.

On May 19, 1967, he retained the title with a tenth-round knockout of Francois Villeiman, and on October 2, he met Charlie Shipes, who was recognized as champion in California.

On April 18, 1968, he retained his title with a fifth-round knockout of Willie Ludick, and on October 21, with a fifteen-round decision over Ramon La Cruz.

Cokes lost the world welterweight title on April 18, 1969, when he was knocked out by Cuban José Nápoles in thirteen rounds in Los Angeles.

He appeared in the 1972 John Huston film Fat City alongside future Academy Award winner Jeff Bridges and Stacy Keach.