Võnnu is a small borough (Estonian: alevik) in Tartu County, Estonia. It is located about 21 km (13 mi) southeast of the city of Tartu. Võnnu has a population of 552 (2011), and is the administrative centre of Võnnu Parish.
Võnnu village and manor were first mentioned in 1341 as Wenden.
St Jacob’s Church of the Estonian Evangelical Lutheran Church (originally constructed, 1232–1236) has been rebuilt several times, and is one of the largest churches in the Estonian countryside.