CARACAS, Venezuela—President Nicolás Maduro’s government declared a 60-day nationwide economic emergency Friday as his embattled administration tries to tackle a deepening economic crisis and undermine the opposition’s new majority in the National Assembly.

The announcement was made hours before Mr. Maduro delivered a much-anticipated state of the union address, where he promised to continue his statist economic model in the face of hardships that he blamed on lower oil revenues and capitalist speculation. But Mr. Maduro acknowledged...