Suure-Jaani is a town in the northern part of the county of Viljandimaa in Põhja-Sakala rural municipality, 25 kilometres north of the town of Viljandi. Until 2017, Suure-Jaani was the administrative centre of Suure-Jaani rural municipality.

Viljandi County is one of 15 counties of Estonia. It is located in southern Estonia bordering Pärnu, Järva, Jõgeva, Tartu and Valga counties as well as Latvia.