In 1879 he became a professor at Bordeaux and in 1889 professor of mediaeval history at the Sorbonne; in 1895 he became a member of the Académie des sciences morales et politiques, where he obtained the Jean Reynaud prize just before his death.
The most important of Achille Luchaire's earlier works is his Histoire des institutions monarchiques de la France sous les premiers Capétiens (1883 and again 1891); he also wrote:
His later writings deal mainly with the history of the papacy, and took the form of an elaborate work on Pope Innocent III. This is divided into six parts:
He wrote two of the earlier volumes of Ernest Lavisse's Histoire de France.