At 39, Renzi will become Italy's youngest premier when he and his Cabinet are sworn in on Saturday. He will also be the third straight premier to come into the office without being elected. The last premier who stood for election was the scandal-tainted Silvio Berlusconi in 2008.
Renzi had been serving as Florence mayor when he engineered a power grab last week to effectively force fellow Democrat Enrico Letta to reluctantly relinquish the premiership after 10 months at the helm of a fragile, often-squabbling coalition.
Renzi told reporters at the presidential palace that he's aiming to give a "strong message" to the international community that his government will enact electoral and economic reforms quickly.
President Giorgio Napolitano urged the new government to swiftly enact the reforms crucially needed to make Italy competitive. "
"We cannot afford the luxury of losing this occasion," Napolitano said.