Kosli is a town and "tehsil" in the Rewari district of Haryana in India.

Kosli is bordered by Jhajjar district to the north.

It is located approximately 80 kilometers southwest of Delhi and is part of the National Capital Region.

According to Haryana State Gazetteer, Kosli was founded in 1193 A.D. by Kosal Dev Singh, the grandson of King of Delhi.

Kosal Dev Singh said to have met the sage Baba Mukteshwar Puri, Kosli engaged in meditation at Koshalgarh Kosli, which was then a dense shrub jungle.