The Ayat is a river in Chelyabinsk Oblast, Russia and Kostanay Region, Kazakhstan. Ayat is formed by the confluence of Karataly-Ayat and Archagly-Ayat. The river flows into the Karatomar reservoir, which is drained by the river Tobol. The length of the river is 117 km, with a catchment area of 13,300 km².