A tsunami warning was issued for areas within 1,000 km (621 miles) of the epicenter of the quake, the U.S.-based Pacific Tsunami Warning Center said. The Chilean Navy also issued a tsunami warning.
The quake's depth was about 15 km (nine miles).
Chile's National Emergency Office (Onemi) said there were no immediate reports of deaths or injuries. Onemi chief Ricardo Toro called on Los Lagos residents to go to safe zones and abandon beaches.
The first tidal waves were expected to arrive at the shoreline in the Los Lagos area at 1 p.m. local time (11.00 a.m. ET), Onemi said.
According to media reports, the quake was felt in the southwest Argentine city of Bariloche.
Chile has a long history of deadly quakes, including a 8.8 magnitude quake in 2010 off the south-central coast, which also triggered a tsunami that devastated coastal towns.