Sandeau was born at Aubusson (Creuse), and was sent to Paris to study law, but spent much of his time in unruly behaviour with other students.
He met George Sand, then Madame Dudevant, at Le Coudray in the house of a friend, and when she came to Paris in 1831 they had a relationship.
The intimacy did not last long, but it produced Rose et Blanche (1831), a novel written together under the pseudonym J.
His major works are: The famous play, Le Gendre de M. Poirier, was one of several which he wrote in collaboration with Émile Augier, the novelist usually contributing the story and the dramatist the theatrical form.
Sandeau had been made conservateur of the Mazarin library in 1853, elected to the Académie française in 1858, and appointed librarian of Saint-Cloud in 1859.