Irpin’ (Ukrainian: Ірпінь; Russian: Ирпень), often called Irpen’ as its name is pronounced in Russian, is a river in Ukraine, a right tributary of the Dnieper.

It is 162 km in length and flows through the city of Irpin’. The location where Irpin' enters the Dnieper river falls into the Kyivs'ke reservoir which the Dnieper forms because of the Kiev Hydro-Electric Power Plant dam. Thus, the Dnieper water level at this location is lifted artificially by about 6.5–7 meters above the natural level. Therefore, the water of Irpin' is pumped into the Kyivs'ke reservoir by powerful electrical pumps, making Irpin' the river that literally flows upwards.

The lands around Irpen' were the heartland of Kievan Rus and the chronicles mention the river in connection with several important historic events, such as the Battle on the Irpen' River of 1321 in which the Grand Duke of Lithuania Gediminas (Gedemin) gained control over the lands of what is now central Ukraine.