Galaxidi dates since 1393 BC. The town was originally built 130 metres above the sea level, on a hill, near the church of St.Blasius and it was called Oianthi.
This church was destroyed by an earthquake and it was rebuilt from preexisting old walls.
All the surrounding area is an archeological site. The town was built two centuries before the Trojan war by Locros, a descendant of Defkalion. After his death a monument was erected to his honour by the Oianthians, called "the Locrion". In one Delphic inscription though it is written that the only sovereign was Armodamos.
For a little while it was also called Katakuzinoupolis, in 1444 A.D., from the name of Constantine Katakouzinos.
Oianthi had signed at that time a treaty with the neighboring city of Horakion (Itea-Xeropigado) for peaceful coexistence and resolution of their differences, which proves the degree of civilization of the two cities.
From the 6th to the 9th century A.D. Galaxidi grew to a famous nautical and urban centre with a chair of the archibishop as shown in a list of the Byzantine emperor Leon the Wise.
The monk Efthymios mentions that during the invasion of the Bulgarians in 981-996 A.D. Galaxidi was a growing city. This is also evident from manuscripts which are saved from the monastery of the Saviour Christ, built by Michael Komnenos.