Aigio, also written as Aeghion, Aegion, Aegio, Egio, is a town and a former municipality in Achaea, West Greece, on the Peloponnese. Since the 2011 local government reform, it is part of the municipality Aigialeia, of which it is the seat and a municipal unit.

Achaea or Achaia, sometimes transliterated from Greek as Akhaia, is one of the regional units of Greece. It is part of the region of Western Greece and is situated in the northwestern part of the Peloponnese peninsula. The capital is Patras which is the third largest city in Greece.