In a symbolic move, the former Italian prime minister Paolo Gentiloni has handed over a small bell to Guiseppe Conte.
But the new government alliance has much work to do after taking three months to be formed following the election in March.
Five-Star Movement leader and deputy premier, Luigi Di Maio, heads the new joint industry and labour ministry where he will roll out a basic income for jobseekers and poorer families.
Matteo Salvini, meanwhile, takes on a role to crackdown on undocumented migrants.
On Monday Di Maio met with a group of food-delivery drivers to discuss their lack of protection. It was his first official engagement.
Guiseppe Conte’s first challenge is a confidence vote. Then he faces a number of international relations obstacles.
He heads to Canada in a few days for the G7 meeting. He has already spoken, on the phone, with French President Macron; opening a dialogue between the two leaders.
But a trickier issue could be the EU. Getting the balance right between confrontation and the need to protect Italian interests won’t be easy but it’s one of the many difficult tasks that will show whether this long-awaited government is working effectively.