Sioni (Georgian: სიონი) is a townlet in Georgia, the part of Tianeti Municipality, in the Mtskheta-Mtianeti region. Located 80 km (50 mi) from the Tbilisi railway station, it arose in 1951 during the construction of the Sioni reservoir. Sioni obtained status of a townlet in 1960. Until the 1970s, it was called Sionmsheni.

Sioni is located in the Ivri River valley, on the banks of the Sioni Reservoir, 32 kilometers from Tianeti.

Before the creation of the Sioni Reservoir, there was a basilica dating from the second half of the 5th century, and several medieval monuments were located in the surrounding area. A large part of these was submerged, and the basilica was dismantled and moved to the Folklore and Architecture Museum in Tbilisi.