Toronto Raptors / Raptors 905 (2022–2023) On July 14, 2022, after being undrafted in the
2022 NBA draft, Harper signed a
two-way contract with the
Toronto Raptors. He made his debut on the court against the Atlanta Hawks.
Bobby Webster noted that
Wayne Embry (the Raptors' senior basketball advisor) was involved in both signing Ron Harper Jr. and drafting his father (
Ron Harper). On December 8, he was waived by the Raptors.
Maine Celtics (2024–2025) After joining them for the
2024 NBA Summer League, Harper signed with the
Boston Celtics on July 14, 2024, but was waived on October 17. On October 26, he joined the
Maine Celtics.
Detroit Pistons / Motor City Cruise (2025) On January 6, 2025, Harper signed a
two-way contract with the
Detroit Pistons. On February 1, Harper set the Cruise record for the most 3-pointers made in a single game by making 11 of his 18 3-point attempts as the Cruise defeated the
Long Island Nets 145 - 132. The record was previously held as a tie between
Deividas Sirvydis and
Stanley Umude who made 7 3-pointers each.
Boston / Maine Celtics (2025–present) On August 16, 2025, the
Boston Celtics signed Harper to a training camp contract. On October 16, following the release of
RJ Luis Jr., Harper was converted into a two-way contract. On February 4, 2026, Harper had his first NBA start against the
Houston Rockets. Harper had 11 points, nine rebounds, and three assists in the 114-93 victory. Harper was also lauded for his lock-down defense against
Kevin Durant. On March 10, Harper had a then career-high 22 points on 8-for-11 shooting, including 6-for-9 beyond the three-point line, in a 125-116 loss against the
San Antonio Spurs. On April 12, Harper scored a career-high 27 points, along with 7 rebounds, four assists, and three steals, in a 113-108 victory over the
Orlando Magic. ==Career statistics==