The Blazers announced Thursday night that Leonard, who has missed Portland's last five games, will undergo the operation on April 8. The team will determine a timetable for Leonard's return after the surgery.
Leonard suffered the injury during a practice on March 16, when he dislocated his left shoulder for the second time this season. He also missed seven games in November because of the same injury.
The 7-foot-1 Leonard averaged career highs of 8.4 points and 5.1 rebounds in 61 games this season, his fourth with Portland.
The Blazers (37-36) have lost eight of their last 12 games but still are sixth in the Western Conference standings, one game ahead of the seventh-place Dallas Mavericks.