In 1956, Marshall won the Mid-American Conference but lost to Morehead (KY) in the first round of the National Collegiate Athletic Association (NCAA) tournament. Marshall finished second in the conference in 1957 and 1958 despite leading the nation in offense in the 1957-58 season. This team also included the school's first All-American, Leo Byrd, and Cebe Price, who was drafted by the Syracuse Nationals of the National Basketball Association (NBA). Greer was All-Conference in 1957 and 1958 and became the school's second All-American. He also set Marshall's career record for field goal percentage (.545) en route to scoring 1,377 points and averaging 19.4 points per game. Greer was chosen by Syracuse in the second round of the 1958 NBA draft.
During his fifteen-year career with Syracuse and the Philadelphia 76ers, Greer was one of the NBA's most dominant guards, averaging 19.2 points per game. When he retired in 1973, Greer held the career record for most games played (1,122) and ranked in the top ten in points scored (21,586), field goals attempted (18,811), field goals made (8,504), minutes played (39,788), and personal fouls (3,825). He was named an all-star ten times and won the Most Valuable Player Award for the 1968 game. Greer's 1966-1967 76ers' team, led by Wilt Chamberlain, ended the Boston Celtics' streak of eight consecutive championships and was named in 1980 as the greatest team in league history. Greer's number 15 jersey was retired by the 76ers and in 1981, he was elected to the Naismith Pro Basketball Hall of Fame.
Greer was honored by his native city of Huntington on two occasions. In 1966, Mayor R. O. Robertson hosted "Hal Greer Day." Twelve years later, 16th Street, which runs by Marshall's campus, was renamed Hal Greer Boulevard.