In 1971, he moved to Paris, where, after an unsuccessful contract with Bayard Presse, he held multiple jobs, notably in advertising.
At this time, he met cartoonists Joëlle Savey, François Bourgeon, and André Juillard.
He published his works in various magazines, such as Triolo, Formule 1, Fripounet et Marisette, Tintin, and Okapi.
In 1982, Dermaut began at Glénat Editions, and, in collaboration with Daniel Bardet, published Les chemins de Malefosse, a historic comic book series.
In 2015, Dermaut wrote the series Rosa, which he based largely on the story of Bernard Ollivier.