He was educated at James Ruse Agricultural High School[5] and then studied medicine at the University of Sydney.
[6] Koo was brought up as an atheist, but the death of his mother while he was training as a doctor at University caused him to reassess his views and he converted to Christianity.
He later was appointed as a minister within the Anglican Diocese of Sydney at St Paul’s Carlingford and North Rocks, where he was eventually made rector, a position which he held for seven years prior to his appointment to the episcopate.
[1] In November 2019, Koo was appointed as Bishop of the Western Region in the Sydney Diocese, a role which involves overseeing congregations in the Blue Mountains, Hills District, Hawkesbury, and Parramatta areas.
[9][3] Koo was consecrated bishop in St John's Cathedral, Parramatta by Archbishop Glenn Davies on 20 December 2019.