Martin announced his commitment to Kansas on May 17, 2021.[8] He was ranked as one of the top-3 transfer players heading into the season.[9] In their 2021-22 season opener, he scored 15 points on 5-of-9 shooting against Michigan.[10] On December 29, 2021, he suffered a right knee injury.[10] That injury kept him ineffective throughout January and caused him to miss seven games in February.[10] He was able to return for the final game of the month, which was a loss to Baylor.[10] He then had 12 points and a season-high three steals in the Big-12 tournament championship game victory over Texas Tech.[10] In the opening round, he had 15 points, four assists, and two steals against Texas Southern.[11] He then went on to have 20 points and 7 rebounds against Creighton the next round, and 23 points in the Sweet 16 against Providence.[11] After Kansas beat Miami to move on to the Final Four, he was named Most Outstanding Player of the Midwest regional.[12] In the national championship game he only scored three points in the first half, but had 11 crucial points after the half, helping Kansas beat North Carolina for its fourth national championship.[13] He is the third Filipino-American basketball player to win a national championship, after Raymond Townsend with UCLA in 1975, and Kihei Clark with Virginia in 2019.[13][14]