In 1801 he was made a member of the Tribunate, and in 1805 a senator of the Empire. In 1814 he voted for Napoleon's abdication, which won for him a seat in the Chamber of Peers after the First Bourbon Restoration. However, during the Hundred Days he returned to serving Napoleon. After the defeat at Waterloo and the subsequent abdication of Napoleon, 1815 Boissy d'Anglas was one of the five commissioners sent by the Provisional Government to try to negotiate peace terms with the Duke of Wellington and Prince Blücher. For his disloyalty to Louis XVIII, on the Second Restoration, he was for a short while excluded.