Nizhyn (Ukrainian: Ніжин) is a city located in the Chernihiv Oblast (province) of northern Ukraine, along the Oster River, 150 km (93 mi) north-east of the nation's capital, Kiev. It is the administrative center of the Nizhyn Raion, though the city itself is also designated as a district in the oblast. Once a major city of the Chernigov Governorate today has estimated population of 76,625 (as of the 2001 census).

The earliest known references to the location go back to 1147, when it was briefly mentioned as Unenezh. In the times of the Polish-Lithuanian Commonwealth, Nizhyn was granted Magdeburg rights (1625) as a self-governing town. Nizhyn was once a major center of Hasidic Judaism and is the site of the Ohel (tomb) of the Hasidic master, Rabbi Dovber Schneuri of Chabad-Lubavitch. It was also the seat of a major Cossack regiment (until 1782) and of the thriving Greek community^{[citation needed]}, which enjoyed a number of privileges granted by Bogdan Khmelnytsky.

In the 19th century Nizhyn became an uyezd capital of the Chernigov Governorate and the biggest city in the guberniya. In 1805, the Bezborodko Lyceum was established there; its graduates include Nikolai Gogol, whose statue graces one of city streets. Nizhyn has also long been noted for its famous cucumbers.