Jaycee Chan, 31, also an actor, is the latest high-profile celebrity to be ensnared in one of China's biggest anti-drug crackdowns in two decades.
Kai Ko, 23, a Taiwanese movie star, was also taken into custody. Police did not provide a clear explanation on why the detentions were announced several days afterward.
Chinese President Xi Jinping expressed an ambition in June to clean the country of illegal drugs and promised severe punishment for offenders. More than 7,800 people have been detained in Beijing alone during the crackdown, police said.
Jaycee Chan's management company, "M'Stones International," issued an apology to the public on his behalf for the "social impact" caused by his detention.
State broadcaster CCTV aired footage of a police search of the younger Chan's home in Beijing in which he is seen showing investigators where he stashed bags of marijuana. Police said they acted on a tipoff from a member of the public.
Chan is accused of accommodating drug users, an offense that carries a maximum jail sentence of three years. Two other people detained in the same case were accused of selling drugs while Ko is accused of drug consumption.