Pinera signed the enactment at the presidential palace in the company of socialist former president Ricardo Lagos, who 15 years ago introduced a number of significant constitutional reforms.
Many stores, subway stations and banks were burned, damaged or looted over the weekend, and some people have reported problems getting cash at ATMs.
The general inspector of police Mauricio Rodriguez added that 11 civilians and 156 officers were injured during the protests, and 49 police vehicles were damaged.
