Born Tsang Koon-yat in Shanghai, China, Tsang attended college in the United States, first at McMurray College in Texas, then at the University of California, Berkeley. He began acting as a teenager in Hong Kong films in the 1950s and in the 1960s became a regular working in a number of classic kung fu films including a recurring role in the long running Wong Fei-Hung series of movies. He would go on to have roles in wuxia TV series, including The Legend of the Condor Heroes and The Return of the Condor Heroes.
Starting with the 1986 film A Better Tomorrow, Tsang would appear in several of director John Woo's movies. He also appeared in the Jackie Chan films Police Story 3 and Rush Hour 2.