Chief Executive Carrie Lam was among the Hong Kong government officials who attended the ceremony.
Hong Kong, a former British colony, was handed back to China in 1997, under an agreement that the territory would enjoy "a high degree of autonomy, except in foreign and defence affairs", for 50 years.
This morning, September 23, the first high-speed rail line linking Hong Kong to the Chinese mainland began operation.
As a result, Hong Kong has its own laws, protections for certain rights and freedoms, and most mainland Chinese laws can not be applied in the territory.
The 142-kilometer railway will open on Sunday, allowing passengers to travel between West Kowloon station in Hong Kong and Guangzhou South station in 47 minutes.
At least two more large-scale cross-border infrastructure construction projects are about to be completed between Hong Kong and the Chinese mainland - the Hong Kong-Zhuhai-Macao Bridge in the west of the Hong Kong SAR and Liantang/Heung Yuen Wai Boundary Control Point in the northeast of the Hong Kong SAR.
"I'm not anxious about the (mainland security) issue".
The 38 "mid- to long-haul" destinations accessed over the wider Chinese high speed network include such as Beijing, Shanghai, Kunming, Guilin, Guiyang, Shijiazhuang, Zhengzhou, Wuhan, Changsha, Hangzhou, Nanchang, Fuzhou, Xiamen and Shantou.
This is the name of Beijing's master plan to combine the cities of the Pearl River Delta region - including Hong Kong, Macau, and nine cities in neighbouring Guangdong province - to foster greater economic and technological development to rival the bay areas of San Francisco and Tokyo. The Greater Bay Area would comprise 68 million people and span 56,500 square kilometers in southern China, an area that is now managed by three governments with three separate borders and three different legal systems.
To unleash the full benefits of the highspeed rail for future passengers, a co-location arrangement has been applied at West Kowloon Station to speed up cross-border passengers' journeys.
"The XRL train has slashed my commuting time to one hour from three hours", said Alex Leung, a Hong Kong entrepreneur working in Shenzhen who is considering moving his office closer to Futian high-speed railway station.
"That's my personal experience, and I'm sure many people in Hong Kong will particularly favor and prefer using highspeed train for this sort of distance".
Directly outside the station is Hong Kong's new arts and cultural hub, the West Kowloon Cultural District.
The Hong Kong section of the Guangzhou-Shenzhen-Hong Kong Express Rail Link (XRL) opened Sunday, Xinhua reported.
"I don't know whether it is really good if we just become another city in the Guangdong province".