Lester del Rosario played for UST Growling Tigers under his father Aric del Rosario, and notably played with Udoy Belmonte, Patrick Fran, Rey Evangelista, Dennis Espino, and Siot Tanquingcen.

[1] In 1992, his first year, del Rosario saw his team losing to FEU Tamaraws due to interruption by a power outage, but due to UAAP Board's decision to reschedule the last 3 minutes of the game, UST ended up losing, 76–87.

[10] He professional scene for Pampanga Dragons in Metropolitan Basketball Association in 1998, when they won championship under his father's tutelage.

[11] Del Rosario served as an assistant to his father when it was appointed as head coach of the Philippine team for the 2003 SEA Games.

[13] Del Rosario served as head coach for Pioneer ElastoSeal Katibays, A PBA 3x3 team, and won a championship in 2021 second conference.