The 24-kilometer-long Shenzhen-Zhongshan Railway, which opened after seven years of construction, will shorten travel times between Hong Kong and cities on either side of the Pearl River Delta.
Xi said the bridge is a record-breaking engineering project on the same level as the Hong Kong-Zhuhai-Macau Bridge.
“This proves that Chinese-style modernization can be achieved through hard work,” he added.
Xi stressed that the link needs to function smoothly and smartly to “play a pioneering role in transportation and promote the integrated development of the east and west of the Pearl River Delta.”
He also called for greater integration of the Gulf region, urging it to become an example of high-quality development and a pioneer of Chinese-style modernization.
The Bay Area refers to Beijing’s plan to develop Hong Kong, Macau and nine cities in mainland China into an economic powerhouse.
Excited Hong Kongers queued at Kwun Tong station at 2pm to board the cross-border bus, the inaugural run of the 44.69 billion yuan ($6.15 billion) route.
The link is designed to handle the huge amount of traffic generated by Bay Area residents.
This includes two bridges, two artificial islands, and an undersea tunnel connecting Zhongshan and Shenzhen.
The eight-lane expressway will cut travel time between Hong Kong and Zhongshan from two and a half hours to one and a half hours because buses and other large vehicles will no longer need to use the Nansha Bridge, north of the old Humen Bridge, to reach destinations on the western side of the delta.
Travel time between Shenzhen and Zhongshan is expected to reduce from two hours to around 30 minutes.
Travel time between Nansha and Zhongshan will be reduced to 15 minutes, while travel time between Shenzhen and Zhuhai or Jiangmen will be halved to just one hour.