Yoncabaşı is a village in Tatvan District, in Bitlis Province, Türkiye. Yoncabaşı lies in the İhtiyarşahap Dağı mountains. It has 882 inhabitants (2022). The nearest city is Tatvan, 8.2 km to the northwest. Among the landmarks around are Saint Anania monastery (15.3 km) and Saint John Monastery, Por (17.1 km).