The 55-year-old man was injured in a blaze in the region of Ilia on the Peloponnese peninsula and died at a hospital, said a fire service official.
Some 120 firefighters, assisted by dozens of engines, were deployed to tame forest fires in Achaia region, which spread fast to the nearby district of Ilia and raged uncontrolled, Reuters reported.
"All forces are making a superhuman effort to tame them," amid winds of up to 120 kph (75 mph), Greek fire brigade spokesperson Vasilis Vathrakogiannis said, as about 45 wildfires broke out in the country within a few hours.
Wildfires are common in the Mediterranean country, but they have become more devastating as summers have become hotter, drier and windier, which scientists relate to climate change.
Residents of several villages in the fire-afflicted areas were told to flee their homes, while some used small buckets to assist in firefighting.
Greek television showed the interior of a stone house gutted by fire.
Civil protection forces have been on alert as the risk of wildfires remains high for Saturday, Vathrakogiannis told a televised briefing.
One forest fire that briefly threatened houses at a coastal town close to Athens was contained earlier on Friday, the fire brigade said.
SD/PR