With his parents' consent, he abandoned this apprenticeship and walked from Caen to Paris to become a student of Jean-Baptiste Regnault (in whose studio he met and became friends with Charles Paul Landon).
On the Bourbon Restoration Robert Lefèvre painted a portrait of Louis XVIII for the Chambre des Pairs and received the cross of the Légion d'honneur and the title of First Painter to the King, losing the latter on the July Revolution.
His most notable history paintings are his Phocion getting ready to drink hemlock, Roger delivering Angélique, Héloïse and Abelard and a Crucifixion for the Mont Valérien.
While he was working on this last painting, the Revolution of July 1830 took place, an event which was to deprive him of his support and official posts.
Ill, depressed and desperate, he committed suicide by cutting his throat at his house on the night of 2/3 October 1830; he was 75 years old.