Born in Aunay-sous-Auneau, Eure-et-Loir, Isambert studied law and, in 1818 (under the Second Restoration of the Bourbons), an attorney at the Cassation Court.

As a member of the Chamber of Deputies, he worked for legislative and administrative reforms in the colonies, and was noted for his attacks on the Roman Catholic Church.

Named counsel at the cassation court on August 27, he edited the Constitutional Charter, and joined the Chamber of Deputies in October of that year.

[2] Isambert voted for the government of Jacques Laffitte, but joined the opposition under the minister Casimir Périer.

In 1834, he founded the Société pour l'abolition de l'esclavage, a militant abolitionist organisation.