Italian President Sergio Mattarella has sworn in Giuseppe Conte as prime minister in Rome's populist government.
Conte is a little-known law professor who gave up a mandate to form a government over the weekend.
The 5-Star Movement and the far-right League revived their alliance after agreeing to substitute the eurosceptic professor, Paolo Savona, as the economy minister. Savona was rejected for the job by the head of state.
"All the conditions have been fulfilled for a political, 5-Star and League government," 5-Star chief Di Maio and far-right League leader Salvini said in a joint statement.
5-Star leader Luigi Di Maio, who had called for the head of state to be impeached, will become the Labour and Industry Minister.
He will have the task of implementing 5-Star's flagship policy of a guaranteed income for the poor of up to €780 per month.
The leader of the League party, Matteo Salvini is to become the interior minister. He has promised to ramp up deportations of irregular immigrants.