Eight died in the worst-hit gambling hub of Macau, where local media showed cars underwater and people swimming along what are normally streets. The enclave's famed mega-casinos were running on backup generators.
One man was killed after being injured by a wall that blew down, another fell from a fourth floor terrace and another was hit by a truck.
The Macau government said a body was found in an indoor carpark early Thursday, but details on the other victims there were not immediately available.
The enclave's sprawling Venetian casino resort had been on back-up power Wednesday and without air conditioning or proper lighting, according to one source, while residents took to social media to complain about city-wide power and mobile phone network outages.
A member of staff at the Grand Lisboa Hotel in central Macau told AFP Thursday that it was still without electricity following the typhoon.
"There is no water and no electricity," the person said, adding that both the restaurant and casino were closed.
Footage showed people holding plastic buckets queuing on the sidewalks to collect drinking water.
Firefighters in the former Portuguese territory have been carrying out rescue work, while a cleanup operation is under way with government departments clearing falling trees and reopening major roads.
Ferry services between Macau and neighbouring Hong Kong resumed Thursday morning but passengers said they experienced delays.
In Hong Kong, Hato -- whose name is Japanese for "pigeon" -- sparked the most severe Typhoon 10 warning, only the third time a storm of this power has pounded the financial hub in the past 20 years.
More than 120 were injured as the city was lashed with hurricane winds and pounding rain. One 83-year-old man earlier thought to be a victim of the weather had committed suicide during the typhoon.
In the neighbouring southern Chinese province of Guangdong, at least four people died and around 27,000 were evacuated to temporary shelters, the official Xinhua news agency said. Nearly two million households were briefly without power.
In Zhuhai, which borders Macau, some 275 homes had collapsed, with the typhoon causing an estimated 5.5 billion yuan ($826 million) in damage, according to the state-run Beijing News.
Hong Kong and the surrounding region is regularly battered by typhoons between July and October.
The city saw its strongest storm in 1962 when the eye of Typhoon Wanda passed over and gusts of 284 kilometres per hour were recorded.
It killed 130 and left 72,000 people homeless in Hong Kong alone.