Sims was drafted by the Knicks in the 2nd round, 28th pick, 58th overall in the 2021 NBA draft. Sims has spent his first three seasons with the Knicks (2021-24). In 119 career games, Sims is averaging 13.5 minutes, 2.6 points, 3.9 rebounds, and 0.5 assists. Sims participated in 2023 NBA Slam Dunk Contest.

Prior to the NBA, Sims played four seasons with the University of Texas (2017-21). In 119 career games with the Longhorns, Sims averaged 20.5 minutes, 6.6 points, 5.4 rebounds, and 0.4 assists.