Cox guided the Braves to their 14th straight National League East division title, while the White Sox won the American League pennant for the first time in 88 years. The White Sox appeared in the World Series for the first time since 1959, and swept the Houston Astros in four games.
In voting by the Baseball Writers' Association of America, Cox out-distanced runner-up Tony La Russa of St. Louis. The Astros' Phil Garner was third in the NL.
Cox was named for the second year in a row and for the fourth time overall. The overall number ties him with La Russa.
In the American League, Guillen beat out Eric Wedge of Cleveland. The New York Yankees' Joe Torre finished third.