Groza was drafted in the 1st round of the 1949 NBA Draft by the Indianapolis Olympians. Groza averaged 23.4 points per game in his rookie season and was named NBA Rookie of the Year — a designation not currently sanctioned by the NBA for the 1949-50 season. He averaged 22.5 points per game over two seasons before being implicated along with college teammates Ralph Beard and Dale Barnstable in a point shaving scandal during the 1948-49 season at Kentucky. NBA president Maurice Podoloff banned all of the implicated players from the league for life.
As a result of this ban, Groza became the first player in NBA history to end his career with a season in which he averaged at least 20 points per game (Groza averaged 21.7 PPG during the 1950-51). In NBA history, only three players have had higher scoring averages in their final NBA seasons: Bob Pettit (22.5 PPG in '64-65), Paul Arizin (21.9 PPG in '61-62), and Dražen Petrović (22.3 PPG in '92-93).
After his playing career ended, Groza became the coach of Bellarmine University (now University) in Louisville, Kentucky. In 1963, Groza led the Knights to a Kentucky Intercolliegiate Athletic Conference title and was named KIAC coach of the year. Groza left Bellarmine in 1966 for a brief coaching and managerial career in the American Basketball Association. Between 1971 and 1975, Groza coached 40 games with the Kentucky Colonels and San Diego Conquistadors and held a number of front office positions, including becoming the Kentucky Colonels' business manager in 1969 and general manager of the San Diego Conquistadors in 1972 (and, later, San Diego's head coach). Groza was 2-0 as coach of the Colonels but 15-23 as coach of the Conquistadors, putting his career coaching record at 17-23 . Groza served as general manager of the San Diego Conquistadors beginning in 1972 until taking over as the team's coach in 1974, replacing Wilt Chamberlain. In 1975 Groza became director of player development for the San Diego Sails of the ABA.