After four years of playing college basketball at UC Davis, Brynton Lemar, after going undrafted in the 2017 NBA Draft, made his first appearance in European basketball in the 2017/18 season, which he started with Nancy and finished with Caen. This was followed by a move to Soprona, Start Lublin, and in the 2020/21 season he wore the jerseys of Gaziantep and Reggiana. He joined Enisey in August 2021, followed by a move to Le Mans. He joined AEK in February 2023 and joined Hapoel Jerusalem last summer.

In the 2023/24 season, he played in 13 regular season games in the Israeli league and averaged 11.2 points, 2.5 rebounds and 1.2 assists per contest.

Lemar has experience playing in international competitions, having played in the FIBA Europe Cup and the Basketball Champions League. In the latter, he played in six games in the AEK jersey and recorded 15.7 points, 2.7 rebounds and 2.0 assists, while in the Hapoel Jerusalem jersey he averaged 7.7 points, 1.8 rebounds and 1.4 assists.