When Hong Kong films started to move towards Mandarin, Kwan's career faltered and joined TVB and acted in various roles.
This beautiful era wherein he was the young lead last until the end of the 1960s, when the arrival of the Mandarin language productions from the Shaw Brothers will impose juvenile faces to the public, such as Jimmy Wang Yu, David Chiang Da Wei or Yueh Hua.
Some returned to theatre, others continued to do movies in Cantonese while participating in productions shot then in Mandarin in big studios such as Shaw Brothers or Cathay Asia Films.
Not unlike in cinema, Kwan Hoi San was able to perform all kinds of characters in the small screen without troubling his audience.
He was, from one series to another, a good family man, a Kung-fu master, a machiavellian godfather, a minister of the emperor, a Taoist magician, a firm manager, a historical character or also a traitor to the country.
Other stars from TVB have confronted him more than once in the long series of the channel: Chow Yun Fat, Carol Cheng Yu Ling and Simon Yam Tat Wah in Brothers/Tsan Ching (亲情), Adam Cheng Siu Chow in Clan of Intrigues/Chor Lau Heung (楚留香), Andy Lau Tak Wah and Tony Leung Chiu Wai in The Duke of Mount Deer/Luk Ding Kei (鹿鼎记), Felix Wong Yat Wah and Ray Lui Leung Wai in Kung Fu Master of Fat Shan/Fat San Chan Sin Sang (佛山赞先生), Stephen Chow Sing Chi in The Justice of Life/Ta Loi Chi Kong Woo (他來自江湖) or also Lau Ching Wan in The Battle Among The Clans/Dai Heung Kong (大香港).
In 1982, in The Demi-Gods and Demi-Devils/Tin Lung Pa Po (天龙八部), he crossed the path of Leung Kar Yan, but also Kwan Chung (关聪), one of his sons.
In the 1980s, just like a Bill Tung Biu, Kwan Hoi San found a second fame within cinema thanks to his successful television career.
In 1991, he won the Hong Kong Film Award and the Taiwanese Golden Horse in the best male supporting role category for his part in Lee Rock by Lawrence Ah Mon.
Jackie Chan and Sammo Hung Kam Bo were enjoying paying tribute to past Cantonese cinema stars by reuniting them in their productions.
Kwan Hoi San in Hard Boiled was the old godfather for whom things were much too complicated because of the young generation of gangsters, led by Anthony Wong Chau Sang, and he was “betrayed” by Tony Leung Chiu Wai.