Plumes of smoke enveloped eastern suburbs of Athens as six planes, three helicopters and about 100 firefighters battled the flames on the lower slopes of Mount Hymettus, about five kilometres east of the city centre.
Local authorities reported outages of power and water supplies to the area.
Residents from nearby homes joined in the fire fighting effort, using branches and shovels in an effort to limit the blaze.
Thousands of hectares of forest and brushland have been burned in massive fires across Greece this summer, after a June heat wave when temperatures reached 46 degrees Celsius.