Prior to college, Lyles attended DeMatha Catholic High School in Hyattsville, Maryland, where he was a three-star recruit.

[4] In his junior season, he averaged 11 points and three assists per game and helped his team reach the Washington Catholic Athletic Conference (WCAC) finals.

[2][6] Lyles also played for Team Takeover on the Amateur Athletic Union (AAU) circuit, competing alongside Josh Hart.

[7] Sources: Lyles competed for the VCU Rams as a freshman in 2013–14 under head coach Shaka Smart, averaging 0.7 points, 0.2 rebounds, and 0.3 assists in only 2.9 minutes per game.

[10] After one semester at Robert Morris, Lyles transferred to the University of Maryland, Baltimore County (UMBC), where he would play for the Retrievers starting in the 2015–16 season.

[11] He made an instant impact as a sophomore for UMBC, averaging 23.0 points, 5.5 rebounds, and 2.8 assists per game and garnering second-team All-America East Conference accolades.

[9][2] In his junior season, Lyles averaged 18.9 points, 6.6 rebounds, and 2.6 assists en route to second-team All-America East honors.

[17] On March 10, in the championship game of the 2018 America East tournament vs. Vermont, Lyles scored 27 points, including a game-winning three-pointer with 0.5 seconds left in regulation.

[9] On March 16, at the first round of the 2018 NCAA Division I men's basketball tournament, Lyles notched a game-high 28 points, shooting 9-of-11 from the field, to lead UMBC to a 20-point upset over top-seeded Virginia.