Tulnici is a commune located in the northwestern part of Vrancea County, Romania. Situated at an altitude of 512 meters (1,680 feet) above sea level, it lies at the foothills of the Vrancea Mountains.
The commune covers an area of 27,576 hectares and is one of the largest administrative areas in the county. It currently consists of four villages: Coza, Greșu, Lepșan, and Tulnici. While it previously included two additional villages, those were split off in 2003 to form the Păulești Commune. Historical records indicate that Tulnici was first attested around the year 1466.