The family makes up all but one of ten positive cases reported in the city yesterday.
The tenth case involved a 70-year-old man who is not related to the family, officials said.
A 24-year-old man and his grandmother, 91, were first confirmed to have coronavirus.
Hong Kong’s Centre for Health Protection later said the man’s father, 68, mother, 57, two aunts and three cousins were also infected.
Officials linking the cases to a hot pot meal on January 26 and said: “Their respiratory samples were all tested positive for novel coronavirus, and they were admitted for isolation and management at Ruttonjee Hospital and Pamela Youde Nethersole Eastern Hospital respectively.”
It brings the total number of cases in Hong Kong to 36, sparking fears of a community outbreak in the densely populated city.
The infected relatives had been to a family gathering at the Lento Party Room in Kwun Tong, where they shared a hotpot and a barbecue meal, reports news.com.au.
There were 19 people at the dinner, including two relatives from mainland China.
The two relatives sought medical attention across the border.
One tested negative for the virus, while the other is still waiting for results.
Coronavirus has now claimed more lives than the 2003 SARS outbreak as the global death toll climbed to more than 800 yesterday with more than 37,000 confirmed cases.
There have been more than 40,000 cases of the virus globally, mostly in China, while the death toll in China now stands at 908.
The new cases come as medical officials confirmed that the virus was airborne.