Police said the order would apply to people aged 11 and over in "certain very crowded zones".
The virus had been circulating more widely in the region since mid-July, they said. Face masks are already compulsory in enclosed public spaces, BBC reported.
Several cities, such as Nice and Lille, have introduced their own additional orders making mask-wearing mandatory in certain outdoor areas.
Paris authorities have not yet detailed which areas will be affected by the new order, which will come into force at 08:00 (06:00 GMT) on Monday.
The zones where masks are mandatory will be evaluated on a regular basis, they said.