Nearly 300 firefighters fought through the night to contain the fire, which burned through pine and olive trees and damaged a number of homes and beach settlements, according to the national fire service.
Several villages and beaches were evacuated on Saturday (July 31) when the fire crossed over the highway connecting Athens to Patras, Greece's third largest city, dividing the area in two.
The fire erupted in the hills of Ziria in Greece's Peloponnese, about 30 kilometres east of Patras, and quickly spread downwards towards the coast.
The blaze burned on multiple fronts and reached the sea, where a fire service vessel helped the firefighting planes and helicopters put out the blaze.
Fifteen people with breathing issues were taken to hospital, according to officials.
Greek authorities had warned the public on Friday (July 30) that there was a high risk of wildfires during a "dangerous" heatwave expected to peak next week with temperatures expected to reach 45 degrees Celsius.