The Regional Flag of the Hong Kong Special Administrative Region of the People's Republic of China depicts a white stylised five-petal Hong Kong orchid tree flower in the centre of a Chinese red field. Its original design was unveiled on 4 April 1990 at the Third Session of the Seventh National People's Congress. The current design was approved on 10 August 1996 at the Fourth Plenum of the Preparatory Committee of the Hong Kong Special Administrative Region. The precise use of the flag is regulated by laws passed by the 58th executive meeting of the State Council held in Beijing. The design of the flag is enshrined in Hong Kong's Basic Law, the territory's constitutional document, and regulations regarding the use, prohibition of use, desecration, and manufacture of the flag are stated in the Regional Flag and Regional Emblem Ordinance. The flag of Hong Kong was officially adopted and hoisted on 1 July 1997, during the handover ceremony marking the handover from the United Kingdom back to China.

Bauhinia × blakeana, commonly called the Hong Kong orchid tree, is a hybrid leguminous tree of the genus Bauhinia. It has large thick leaves and striking purplish red flowers. The fragrant, orchid-like flowers are usually 10 to 15 centimetres across, and bloom from early November to the end of March. Although now cultivated in many areas, it originated in Hong Kong in 1880 and apparently all of the cultivated trees derive from one cultivated at the Hong Kong Botanical Gardens and widely planted in Hong Kong starting in 1914. It is referred to as bauhinia in non-scientific literature though this is the name of the genus. It is sometimes called the Hong Kong orchid. In Hong Kong, it is most commonly referred to by its Chinese name of 洋紫荊 (yèuhng jígīng).