Prime Minister Jean Castex said the tougher restrictions followed a clear acceleration in the spread of the coronavirus, with France now in the grip of a third wave.
"The moment has come to go further, with more demanding restrictions where things are most critical," Castex told a news conference.
The lockdown will be imposed on the 16 hardest hit departments, the prime minister said, including Paris and its surroundings, as well as parts of the north. It takes effect from midnight on Friday.
Schools will stay open and people will be allowed to exercise outdoors within a 10 km (6.2 miles) radius of their homes. People living in these areas would not be allowed to travel to other parts of France without a compelling reason.