Axioupoli, known until 1927 as Boymitsa, is a small town and a former municipality in the former Paionia Province of Kilkis regional unit, Greek Macedonia. Since the 2011 local government reform it is part of the municipality Paionia, of which it is a municipal unit. The municipal unit has an area of 284.406 km2. In 2021 the town had a population of 2,834, and the municipal unit 4,794.

The Vardar or Axios is the longest river in North Macedonia and a major river in Greece, where it reaches the Aegean Sea at Thessaloniki. It is 388 km (241 mi) long, out of which 76 km (47 mi) are in Greece, and drains an area of around 25,000 km2 (9,653 sq mi). The maximum depth of the river is 4 m (13 ft).