A three-time All-State selection at Crispus Attucks High School in Indianapolis, Indiana, the "Big O" attended the University of Cincinnati, where he established 19 school and 14 NCAA records and was a three-time College Player of the Year and national scoring leader.
The 6-foot-5, 220-pound Robertson co-captained the 1960 Olympic gold medal team, called by some the greatest assemblage of amateur basketball talent ever. His 14-year NBA career as a point guard with the Cincinnati Royals and Milwaukee Bucks included Rookie of the Year honors in 1961, three All-Star Game Most Valuable Player awards (1961, 1964, 1969), and the 1964 NBA MVP Award. His best statistical season was 1961-62, when Robertson averaged a triple-double for the entire season: 30.8 ppg, 11.4 apg and 12.5 rpg, a feat that has never been duplicated. He earned All-NBA honors 11 times and led the Royals and the Bucks to 10 playoff berths. In 1971, Robertson teamed with Kareem Abdul-Jabbar to give the Bucks their only NBA title.
Robertson ended his career with 26,710 points (25.7 per game), 9,887 assists (9.5 per game) and 7,804 rebounds (7.5 per game), and was the all-time leader in career assists and free throws made.