Born to a Jewish family in Frankfurt, he was educated at the universities of Bonn, Berlin, and Leipzig.
He went to France, and continued his studies at Paris, graduating as Docteur ès lettres in 1845, and becoming "agrégé" in 1848.
Appointed professor of ancient literature at the University of Besançon, he was in 1872 elected dean of the faculty.
In 1876 he was called to Paris to fill a vacancy as instructor at the École Normale Supérieure and to assume charge of the École Pratique des Hautes Études, both of which positions he resigned in 1891.
Weil edited the poems of Aeschylus, eight tragedies of Euripides, and the orations of Demosthenes.