It is one of the oldest zoological parks in India that was opened to public on February 4, 1974. Spanning over an area of 76 ha, it is situated in a man-made forest. The park is almost like a zoo with animals housed in open and moated enclosures. This gives them ample space to live and move about freely. The enclosures have been designed such that one enclosure is not visible from the other, thereby letting the animals avoid feeling the psychological pressure of being in the vicinity of another animal.

The park has been named after British industrialist George Burney Allen, who was also a botanist and contributed majorly to the zoo's development. It started with a lone otter as its first animal and now visitors can find Alexandrine parakeet, bar-headed geese, Brahminy duck, grey pelican, orangutan, Hamadryas baboon, spotted deer, sloth bear, Gangetic ghariyals, Asiatic tigers and chimpanzees here. The zoological park has been selected as a conservation breeding centre for swamp deer, which is an endangered species. Also known as barasinga, it is endemic to the swampy areas of the Terai tract of Uttar Pradesh.