The vote in the Senate - 156-140, with 16 abstentions - means, however, that Mr Conte does not have an absolute majority in the upper chamber.
Opposition parties say they plan to ask President Sergio Mattarella to intervene to force him to resign.
Mr Conte, a law professor, has led a centrist coalition since 2018.
The main parties in his coalition are the anti-establishment Five Star (M5S) and the centre-left Democratic Party (PD).
