Carlton attended Charlestown schools and starred in basketball, soccer, and baseball at Charlestown High School. He played professional baseball for the Boston Red Sox and the Chicago White Sox from 1969 to 1993, setting several records including most home runs by a catcher and most games caught. He was honored as the first ever unanimous choice Rookie of the Year in 1972, was voted to the American League All Star team eleven times, and was inducted into the Baseball Hall of Fame in 2000.