Tsang had been undergoing seven days of quarantine after returning from Singapore on Monday and was found collapsed on the floor of his hotel room by staff on Wednesday, according to the South China Morning Post and other media.
The South China Morning Post said Tsang was 87 but other sources gave his age as 86.
No cause of death was given and the paper said he had tested negative for the virus and had no underlying medical conditions.
In all, Tsang had some 237 acting credits, mainly in Hong Kong film and television productions, and especially in detective and martial arts movies, according to his IMDb page.
Born in Shanghai, Tsang began acting after obtaining an architecture degree at the University of California, Berkeley, making his debut in 1955. In 1969 alone, he was credited in more than 20 movies and continued working up to the time of his death.
Tsang was married three times and had a son with his first wife, Lan Di, and a daughter with his second wife, Barbara Tang.
Hong Kong is dealing with a renewed outbreak in cases of the highly transmissible omicron variant and requires all inbound travelers to undergo quarantine for up to 14 days.