"With a catastrophe of this magnitude, with no water or power, the population is understandably overwhelmed by anguish and we're losing the sense of law and order," Pinera, who won the January 17 election to succeed Bachelet, told reporters.
In such circumstances, he said, "we have to make use of all our resources, and our armed forces are ready to help in times of crisis and catastrophes."
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Defense Minister Francisco Vidal earlier said the military "were at work from minute one" of the catastrophe.
The 8.8-magnitude earthquake devastated Chile's second-largest city Concepcion, 500 kilometers (310 miles) to the south, and nearby towns, killing more than 700 people with hundreds more missing.
In parts of Concepcion looters ran amok Sunday as they grabbed all they could carry from shops and businesses reduced to rubble by the quake. Authorities have declared a curfew in the city to try to curb the lawlessness.
Pinera, who will take office March 11, said local authorities "tell me that tonight we'll be dealing with a very difficult law enforcement situation, especially in Concepcion," which with more than 600,000 people is the second-largest city in Chile.
The 60-year-old billionaire called on all Chileans to pitch in and help in relief operations and said he was meeting with his incoming cabinet to plan out Chile's massive rebuilding effort, which some estimate will likely cost 15-30 billion dollars.
