The Kempendyay (Russian: Кемпендяй; Yakut: Кэмпэндээйи) is a river in Yakutia (Sakha Republic), Russia.

There are deposits of rock salt in the Kempendyay basin, as well as a mud bath resort.

It heads first roughly southwestwards and in its last stretch, shortly after Kempendyay village, it bends and heads northwestwards strongly meandering within a floodplain among oxbow lakes.

Finally the river joins the right bank of the Vilyuy 737 kilometres (458 mi) from its mouth.

[3][4] The largest tributary of the Kempendyay is the 47 kilometres (29 mi) long Ulakhan-Karyalaakh that joins it from the right.