Martin had a career-high 31 points to go with eight assists in a 95–88 overtime win over Arizona on January 31, 2019.[4] At the conclusion of the regular season, Martin was named first-team All-Pac-12.[5] He averaged 19.1 points (second in conference), 4.1 assists and 3.1 rebounds per game as a junior, and he led the Pac-12 with a 2.4 assist-to-turnover ratio. Following the season, Martin declared for the 2020 NBA draft.[6] On August 2, he announced he was withdrawing from the draft and returning for his senior season.[7] On April 6, 2021, he declared for the 2021 NBA draft. He maintained his college eligibility and entered the transfer portal.