- ABR in situated at the southern-most end of the Western Ghats and spread over two southern states Kerala and Tamil Nadu.
- It was established in 2001.
- It is named after Agastya Mala peak that rises up to almost 1868 metres above sea level, in Thiruvananthapuram, Kerala.
- In March 2016, it was included in the World Network of Biosphere Reserves of UNESCO.
- ABR covers an area of 3,500 sq km at an altitude ranging from 100 metres to 1,868 metres above the Mean Sea Level.
- It covers Peppara and Shendurney wildlife sanctuaries and parts of the Neyyar sanctuary in Kerala and the Kalakad Mundanthurai Tiger Reserve of Tamil Nadu.
- Its flora mostly consists of tropical forests and is home to 2,254 species of higher plants including about 400 that are endemic.
- About 400 Red Listed Plants, 125 species of orchids and rare, endemic and threatened plants have been recorded from the reserve.
- It is also home to rare endimic animals include tiger, Asian Elephant, and Nilgiri Tahr.
- It is home to Kanikaran tribe, one of the oldest surviving ancient tribes in the world.