In his sophomore season, he averaged 19 points per game and was named most valuable player (MVP) of the Greater Spokane League.

[2] As a junior, he averaged 23 points, 11 rebounds and five assists per game and won the Class 4A state title while earning tournament MVP honors.

[4] In his senior season, he averaged 21.6 points, 7.1 rebounds and 3.8 assists per game, helped Gonzaga Prep win a second consecutive 4A state championship.

He was the unanimous MVP of the state tournament and recognized as Associated Press 4A Player of the Year and Washington Mr.

[9] On June 27, 2024, Watson was selected with the 54th overall pick by the Boston Celtics in 2024 NBA draft[10] and on August 2, he signed a two-way contract with them.