The Senate backed the new alliance between the anti-establishment Five Star Movement (M5S) and the centre-left Democratic Party (PD) by 169 votes to 133.
It was the second of two mandatory votes of confidence to confirm the government.
MPs in the lower house gave their own seal of approval on Monday evening with a 343-263 ballot in favour.
Conte, who is on his second mandate as prime minister, said the vote signalled “a new beginning for Italy, a reforming season of revival and hope”.
“The constitution and respect for our institutions will be our compass, and the interests of Italians our goal,” he added.
Though the new government has been given a green light, many challenges lie ahead.
Its first task will be the 2020 budget, which must be submitted to parliament by the end of September, and then to Brussels by October 15.
Italy has the second-largest debt burden in the EU as a proportion of economic output.