Kwok competed for Singapore in the men's 50 m freestyle at the 2000 Summer Olympics in Sydney. He achieved a FINA B-cut of 23.72 from the Southeast Asian Games in Bandar Seri Begawan, Brunei. He challenged seven other swimmers in heat four, including Kyrgyzstan's Sergey Ashihmin, Goodwill Games silver medalist for Russia, and Kazakhstan's two-time Olympian Sergey Borisenko. Diving in with a 0.73-second deficit, Kwok scorched the entire race to share a fourth seed with Peru's Luis López Hartinger in an exact time of 24.00, but finished outside an entry standard. Kwok failed to advance into the semifinals, as he placed forty-ninth overall in the prelims.