A new rule on Monday mandating face mask on Paris river and canal banks as well as some busy streets came into force at 8 a.m (0600 GMT).
The capital is the latest French city to make masks obligatory in some outdoor areas.
They are already obligatory nationwide in most indoor spaces open to the public.
France is currently seeing an uptick in coronavirus infections, with 2,288 new cases reported in 24 hours as of Friday.
However, the number of severe cases in intensive care remained stable at 383.
At the peak of the epidemic nationally in early April, there were more than 7,000 patients in intensive care.
The French COVID-19 death toll stands at 30,324, one of the highest in Europe.
However, the move to impose masks outdoors had so far divided experts.
Some said it would help prevent a serious resurgence of the epidemic, others said the vast majority of infections took place indoors.