Pictures posted on social media showed enormous plumes of smoke billowing into the city's skyline as firefighters rushed to the historic site.
According to French newspaper Le Monde, the fire broke out in the attic of the historic monument before spreading to engulf a large section of the roof.
A spokesperson for the cathedral said the blaze was first reported at 5.50pm (GMT) and the building was evacuated soon after.
Officials in Paris said the fire could be linked to renovation works being carried out at the cathedral.
The cathedral is one the finest example of French Gothic architecture in Europe, and one of the most visited buildings in the world.
Notre Dame - which means 'Our Lady' - was build in 1160 and completed by 1260, and has been modified on a number of occasions throughout the century.
