Bostjan Nachbar began his pro career in the 1997-98 season as a member of KK Union Olimpija. Along with this team, he played in the Euroleague and had statistics of 2 rebounds and 7 points per game. During the 2000-01 season, when he became associated with Benetton Basket Treviso, he was the youngest Italian league player. When he played in the Euroleague for this team, he recorded 4 points and 2 rebounds. In the next season, he improved his statistics to 4 rebounds and 13 points per game and played a major role in assisting Benetton to reach the final four of the Euroleague. In 2002, he won the Italian Supercup and Italian Championship.
He played in the NBA from 2002 to 2008. On 20th July 2008, he signed a deal with Dynamo Moscow, the Russian League Club, which was for 3 years and the amount was 18 million euros.
Bostjan Nachbar played for Houston Rockets from 2002 to 2004, New Orleans/Oklahoma City Hornets from 2004 to 2006 and New Jersey Nets from 2006 to 2008. He appeared in 317 games in the NBA, wherein he played for 5628 minutes. His field goal percentage was 0.406, 3-point field goal percentage was 0.375 and free throw percentage was 0.784. He accrued 283 assists, 698 personal fouls, 836 rebounds and 2252 points.