On September 22, Luka Samanic agreed to a training camp contract with the Boston Celtics. On Monday, Boston released him. Samanic, 22, was selected by the San Antonio Spurs with the 19th overall pick in the 2019 NBA Draft, and he played for them for two seasons. The Croatian forward ultimately participated in 36 regular-season games with San Antonio, averaging just 3.8 points and 2.2 rebounds in around 9.9 minutes per game.
Luka Samanic was released by the Spurs just before the 2021–22 season began, and the New York Knicks quickly offered him a two-way deal. Samanic had a two-way contract with the Knicks, but he never participated in a game with them. Instead, he played in just one game with the Westchester Knicks in the G League, when he scored 26 points and pulled down 9 rebounds in 35 minutes.