He spent his entire career in the Habsburg Netherlands (present-day Belgium) where he led important architectural and urbanistic projects such as the Place Royale/Koningsplein and the new 'Palace of the Council of Brabant' which today houses the Belgian Parliament, both in the city of Brussels.

Guimard was involved in the design and execution of numerous mansions erected in a uniform style around Brussels Park such as the Hotel Errera.

This commission was executed in collaboration with the sculptor Gilles-Lambert Godecharle who also made the designs for the relief decorating the pediment of the Palace of the Council of Brabant.

After the death of Charles Alexander of Lorraine the government of the Habsburg Netherlands was entrusted to Archduchess Maria Christina of Austria and her husband Albert of Saxe-Teschen.

As also Dewez had fallen into disfavour - officially due to shortcomings in his designs for the Vilvoorde prison - they choose for new architects to work in their service such as Charles de Wailly and Louis Montoyer.

Ironically the last official commission that Guimard received was a triumphal arch erected in Brussels at the occasion of the Triumphant Entry of the new Governors into their Capital (1781).

After the occupation of the Habsburg Netherlands by the French revolutionary troops Guimard returned to his country of origin where he was named professor of the Ecole Centrale in Tours in 1796.