On half pay during the Bourbon Restoration, he rejoined Napoléon's Imperial Guard during the Hundred Days.

From 1832 to 1839 Magnan served in Belgium as part of a French force stationed their to saveguard the newly won Belgian independence.

In July 1849 he was given command of the 4th military Division in Strasbourg, the same year he became a deputy for the department of the Seine.

In June 1851 he became commander of the army in Paris in which function he was one of the principal organizers of the coup d'État of 2 December 1851.

The next year Napoléon III made him a senator and granted him the title of Marshal of France.