The 54-year-old said he wanted to "give everything to France" as he launched his campaign.
He added that he "cannot be prime minister while being a candidate" and that he will resign from the government on Tuesday.
Je suis candidat à la présidence de la République. MV— Manuel Valls (@manuelvalls) December 5, 2016
On Twitter, Valls said his candidacy "is also a revolt against the idea that the left is disqualified from this presidential election".
Valls will face other contenders in the Socialist Party's primary next month and, if successful, he will then go head-to-head with Francois Fillon and Marine Le Pen in April, when the first round of the presidential election will kick off.
He has been President Francois Hollande's PM since March 2014, after being his "top cop" interior minister for two years.
It was expected that Valls would run for the job after Hollande announced last week that he will not run for re-election.