Born in Pechelbron, France, Le Bel came from a family with oil interests. He was a student at the Ecole Polytechnique and for a short while was assistant to Charles Würtz at the Ecole de Médecine. He sold his share of the family oil interests and devoted himself to independent scientific research.

He is best known for his account of the asymmetric carbon atom, although his achievement was overshadowed by the almost simultaneous account given by Jacobus van't Hoff. Le Bel's account was published in November 1874, two months after that of van't Hoff. Their work is virtually identical; what difference there is arises from a difference of origin. Le Bel wished to explain the molecular asymmetry of Louis Pasteur while van't Hoff was more concerned with understanding the quadrivalent carbon atom recently introduced by August Kekulé.