Played in Major League Baseball as an outfielder from 1969 through 1986, most notably as an integral member of the Cincinnati Reds, with whom he won two World Series championships, in 1975 and 1976. He also played for the San Francisco Giants, New York Mets and the Chicago White Sox.

A five-time All-Star, Foster was one of the most feared right-handed sluggers of his era, leading the National League in home runs in 1977 and 1978, and in RBIs in 1976, 1977, and 1978. He won the National League's Most Valuable Player Award in 1977 and a Silver Slugger Award in 1981.