The Philippine seismology agency Phivolcs said tsunami waves could hit the Philippines by midnight local time and could continue for hours.
The US Tsunami Warning System said there could be waves of up to three metres above the tide level along some Philippine coasts.
"Boats already at sea during this period should stay offshore in deep waters until further advised," Phivolcs said, asking people living near the coast of Surigao Del Sur and Davao Oriental provinces to "immediately evacuate" or "move farther inland".
The Japanese broadcaster NHK said tsunami waves of up to a metre were expected to reach Japan's southwestern coast about 30 minutes later - by 1.30am on Sunday.
Phivolcs said it did not expect significant damage from the tremor itself but warned of aftershocks.
Raymark Gentallan, local police chief of the coastal town of Hinatuan near the earthquake's epicentre, said power has been knocked out since the quake struck but disaster response teams have not registered any casualties or damage yet.
Earthquakes are common in the Philippines, which lies on the "Ring of Fire", a belt of volcanoes circling the Pacific Ocean that is prone to seismic activity.
The US Geographic Survey said a quake of magnitude 7.6 struck at a depth of 32km at 10.37pm Philippines time.
The Joint Australian Tsunami Warning Centre said there was no tsunami threat to the Australian mainland, islands or territories.
