The FN came first with between 27 and 30 per cent of the vote nationwide and topped the list in at least six of 13 regions.
How the regions voted
FN leader Marine Le Pen and her 25-year-old niece Marion Maréchal-Le Pen headed slates that broke the 40 per cent mark in Nord-Pas-de-Calais-Picardie in the north east and in Provence-Alpes-Côte-d'Azur in the south east.
They tapped into voter anger over a stagnant economy and security fears in the aftermath of the 13 November Paris attacks and Europe's refugee crisis.
The ruling Socialists have withdrawn their candidates from the two regions in the hope of blocking the FN from power and are debating withdrawing in Alsace-Lorraine-Champagne-Ardenne in the east.
Nicolas Sarkozy's mainstream right Republicans have ruled out withdrawing in any region.
Turnout was about 50 per cent, higher than the last regional elections in 2010.