The Ayat (Russian and Bashkir: Аят, Ayat; Kazakh: Аят: Aıat) is a river in Chelyabinsk Oblast, Russia and Kostanay Region, Kazakhstan.

The length of the river is 117 km, with a catchment area of 13,300 km².

[1] Much of the basin is formed by 383 drainless lakes (total area 208 km².).

Russian part of the river has a length of 23 km and a watershed area of 8571 km².

[1] The soils of the basin are mostly sandy and loam, occasionally salt.