At one point a super typhoon and one of the strongest storms in the Pacific this year, Champi is weakening though still packing gusts of around 126km/h near its centre, according to Taiwan's Central Weather Administration.
The storm was about 150km east of Taiwan, having glanced off the island's northeastern coast in Yilan County early on Saturday, the CWA said.
The centre of the storm turned south, hugging the Yilan coastline before making a rare loop offshore and moving northward away, triggering gusts of about 227km/h in some coastal areas, knocking down power lines and sending roof tiles flying.
"It was most terrifying around midnight," said a retired teacher surnamed Lin as he inspected downed banana trees in his garden in Yilan. "It was a sleepless night. I haven't seen anything like this in many years."
The storm's forecast track shows it turning north, tracking up the Chinese coast and eventually moving into southern Japan.
Taiwan's fire department said the death toll remained at one, a man swept away by waves from the island of Liuqiu, with 527 injuries during the heavy wind and torrential rain.
Taipower said at one point more than 288,000 homes had lost electricity, though most had been reconnected.
The transport ministry said 242 flights were cancelled, an improvement from Friday, when the number was almost 1000.
In the capital Taipei, there were downed trees and on-off squally rain showers.
A swathe of northern and central Taiwan, including Taipei, declared a second day of office and school closures on Saturday.
Taiwan is generally well prepared for typhoons, which keeps casualties low. Although more common in summer, the storms can strike in autumn too.
China's emergency management ministry sent a team to the eastern province of Zhejiang as Champi approached, warning of strong winds and heavy rain through Sunday. It said 400 rescue workers and 600 pieces of equipment had been readied, while more than 41,000 firefighters were on emergency duty.
In Taizhou, a city on Zhejiang's coast, more than 3800 fishing boats returned to harbour, offshore fish-farm workers were brought ashore and 2084 island visitors were evacuated, state media reported.
Authorities halted 25 offshore construction projects and suspended 18 passenger ferry routes.
