Taiwanese authorities have warned that Bavi could bring up to 1m (39 inches) of rainfall. Some 29,000 soldiers have been put on standby to help with relief efforts, according to the island's defence ministry.
Bavi is set to be the largest storm, by size, to hit the island since 1987, Taiwan's Central Weather Administration told Reuters.
Farmers across the region rushed to harvest or protect their crops while the weather held earlier on Friday, while fishermen made sure to secure their vessels tightly.
"Don't be fooled by the nice and calm weather now. A storm like this could be the most terrifying," 60-year-old fisherman Chen Ming-hui told Reuters.
Thousands of sandbags have been distributed to residents and shop-owners in flood-prone areas.
Across the strait, China has also warned of "significant impact" from the typhoon that could move northward after smashing into the south-eastern Fujian province.
"Bavi's large size and abundant energy mean its remnants and outer rainbands could move from Jiangsu and Anhui provinces toward the Bohai Sea region," said Ma Jun, director of China's Institute of Public and Environmental Affairs.
The northern provinces, which have "less experience" dealing with typhoons in comparison with the south, should "strengthen preparations", he warned.
Some forecasts suggest Bavi could make landfall twice in China.
In Japan, residents on the remote Sakishima Islands are also on high alert. Photographs shared online show some of them taping up windows and draping windproof nets across their homes and shops.
Various airlines have grounded flights in the region. Japan Airlines, for instance, has axed more than 100 flights for Friday and Saturday, disrupting travel for nearly 20,000 passengers.
All Nippon Airways, another Japanese carrier, has cancelled more than 160 flights through Sunday, also affecting about 20,000 people, according to Reuters.
Thai Airways and Malaysia Airlines have also grounded flights to and from Taipei.
Parts of southern China are still reeling from the devastation brought by Typhoon Maysak earlier this week.
Maysak left at least 39 people dead, with rescuers still combing through wreckage for missing people. More than 130,000 were evacuated, mostly in the Guangxi region.
Maysak killed large swathes of livestock and resulted in massive agriculture loss. It also spurred two rare tornadoes in the central Hubei province.
