[2] Growing up in Regents Park,[3] his father ensured Māori culture was prevalent for Harrison and his older brother as youths.
[1] Harrison played basketball at the Logan Metro Indoor Sports Centre and attended John Paul College in Brisbane.
[3] Harrison joined the Brisbane Bullets of the National Basketball League (NBL) as a development player for the 2017–18 season.
[2] In the 2022 off-season, Harrison underwent elbow surgery after battling through pain over the previous two seasons that had been caused by a stress fracture.
[5] He participated in all but one game in the 2023–24 NBL season, averaging 9.6 points, 6.2 rebounds, and 1.4 blocks, establishing himself as the starting center.
[15] Harrison joined the Nelson Giants of the New Zealand NBL for the 2019 season, where he averaged 13.1 points, 6.2 rebounds, 1.2 steals and 1.2 blocks in 18 games.
[22] Harrison's family hail from the Coromandel Peninsula in New Zealand, with roots in the Ngāti Porou and Ngāpuhi iwi.