[1] He committed to playing college basketball for Presbyterian, the only NCAA Division I program to offer him a scholarship.

During his redshirt year, Flagler improved his all-around game by practicing against Jared Butler, Davion Mitchell and MaCio Teague.

As a sophomore in 2021, he assumed a sixth man role for Baylor, which finished with a 28–2 record and won the first National championship in school history.

After going undrafted in the 2023 NBA draft, Flagler signed with the Oklahoma City Thunder on October 19, 2023, but was waived the next day.

[13] Flagler's older brother, DuVaughn, played college football as a wide receiver at Gardner–Webb and is an elementary school principal.