The Aïr and Ténéré National Nature Reserve (French: Réserves naturelles de l'Aïr et du Ténéré) is a national nature reserve in Niger. It includes several overlapping reserve designations, and is designated a UNESCO World Heritage Site. It covers both the eastern half of the Aïr Mountains and the western sections of the Ténéré desert.

It has been identified by BirdLife International as an Important Bird Area. The mountains are an important spot for afrotropical and palaearctic migratory birds.

The Aïr and Ténéré Natural Reserves UNESCO World Heritage Site was established in 1991, and designated as a site in danger in 1992. It was designated under criteria vii, ix, x, and is designated #573. The entire reserve covers 77,360 square kilometres (29,870 sq mi), which made it the second largest nature reserve in Africa, and the fourth largest in the world.

UNESCO's Aïr and Ténéré Natural Reserves include two parts:

Aïr and Ténéré National Nature Reserve

IUCN type IV

Established 1 January 1988

64,560 km²

Aïr and Ténéré Addax Sanctuary

Strict Nature Reserve IUCN type Ia

Established 1 January 1988

12,800 km²

In 2023, UNESCO reported that the reserve was under threat due to civil unrest and mining. Though illegal activities continue to threaten the reserve, local involvement has helped control gold panning.

The 2023 UNESCO report told of four ecological missions. These missions confirmed Dama and Dorcas gazelles and Barbary sheep were still present on the reserve. The addax has not been sighted in 20 years. As for birds, 50 species have been observed with the number of Nubian bustards showing a sharp descrease. In contrast, 165 species of birds were observed in the initial UNESCO listing. The declining biodiversity in the reserve is one of the reasons it is listed on the World Heritage in Danger list due to the flagship species significance in the "outstanding universal value" of the site.