The Boundaries of Hong Kong, officially the Boundary of the Administrative Division of the Hong Kong Special Administrative Region of the People's Republic of China, is a regulated administrative border with border control in force under the One country, two systems constitutional principle, which separates the Hong Kong Special Administrative Region from mainland China, by land border fence of 30 km (19 mi) and maritime boundary of 733 km (455 mi), enforcing a separate immigration and customs-controlled jurisdiction from mainland China.

Hong Kong is a special administrative region of the People's Republic of China. With 7.4 million residents of various nationalities in a 1,104-square-kilometre (426 sq mi) territory, Hong Kong is one of the most densely populated territories in the world.