Niari (can also be written as Niadi[2]) is a department of the Republic of the Congo in the western part of the country.

It borders the departments of Bouenza, Kouilou, and Lékoumou, and internationally, Gabon, the Democratic Republic of the Congo, and the Cabinda portion of Angola.

The regional capital is Dolisie.

According to an administrational reorganisation of 2012, Niari Department is divided into fourteen districts and two communes not belonging to any district:

This Republic of the Congo location article is a stub.