"The national quarantine will be extended to at least May 3," Conte said at his address. "The decision was not an easy one, but it was what the situation required."
The prime minister's announcement came about one month after the first decree went into force. Since then, Conte has periodically strengthened the terms of the lockdown and extended its length.
Before this extension, the measures were scheduled to be lifted Monday, though reports began circulating on Thursday that it would be extended into May after Conte held a conference call with trade union leaders.
Italy was the first country in Europe to issue a national lockdown as a way to curb the spread of the virus.
The extension means that for an additional 20 days, residents in Italy will not be able to leave their homes except for "vital" reasons, such as food shopping or medical visits.
Conte said that he wanted to loosen the terms of the lockdown "as soon as possible", and that if changes were warranted they cold be loosened before May 3.
He said some activities -- notably stores that sell goods for small children -- would be allowed to re-open starting April 14.
Italy remains one of the countries hit hardest by the coronavirus pandemic, with nearly 19,000 deaths and nearly 150,000 infections.
More than 350,000 people tuned into Conte's address, which was aired on the social media platform Facebook.