The right-handed pitcher appeared in 17 games (with five starts) over parts of four seasons in Major League Baseball (1955–1958) for the Kansas City Athletics.

The Montebello, California native was listed as 6 feet 2 inches (1.88 m) tall and 210 pounds (95 kg).

In the Majors, Cox compiled a career record of 1–4, with his lone victory coming on July 13, 1957, in a 6–4 win over the defending world champion New York Yankees.

[1] In that game, Cox relieved starting pitcher Arnie Portocarrero in the sixth inning with the Yanks leading 4–2.

Cox exited the game in the eighth, and Tom Morgan nailed down the save for Kansas City.