The Shenzhen-Zhongshan link, which is set to shorten travel time between Hong Kong and cities on the other side of the Pearl River Delta, will open to traffic at 3pm on Sunday.
The 24km-long (15 mile) crossing, situated 30km south of the Humen Bridge that links Guangzhou and Dongguan, will connect the two sides of the Pearl River Delta within mainland China.
It will connect the city of Zhongshan to Shenzhen via two bridges, two artificial islands and one undersea tunnel that is 6.8km long and 46 meters (151 feet) wide.
Hong Kong-based operators of intercity coaches have suggested the new link will trim travel time between Hong Kong and Zhongshan from 2½ hours to under two hours.
The Hong Kong-Zhuhai-Macau Bridge is located 31km south of the new link and currently only connects to Hong Kong at its eastern end. But authorities have recently proposed to add a road extension to Shenzhen to make better use of the mega bridge that opened in 2018.