Jonionys is a village in Varėna District Municipality, in Alytus County, Lithuania. Jonionys lies at 87 m above sea level. It has 37 inhabitants (2021). The nearest city is Alytus, 27 km to the north. Near the border: Belarus, 21 km. Among the landmarks around are Grūtas Park (15.5 km), Church of the Assumption, Merkinė (3.3 km) and Joy of All Who Sorrow Church (18.5 km).