Boffrand was received by the Académie royale d'architecture in 1709. The following year he was among those employed in the additions to the Palais Bourbon. In 1732, he was appointed "inspecteur général des ponts et chaussées" and produced plans for restructuring Les Halles. He was a participant in the competition for the design of Place Louis XV. Named chief architect to the hôpital général in 1724, he constructed in the Île de la Cité a foundling hospital, the "Hôpital des Enfants Trouvés" (1727, demolished). Boffrand also worked for the hospitals at the Salpêtrière, at Bicêtre, and at the Hôtel-Dieu. He built a series of "hôtels particuliers" in Paris as speculative business enterprises. Of the inventive spatial arrangements in the hôtel that swiftly became the Hôtel Amelot de Gournay, Germain Brice remarked in his early 18th-century guidebook that "one will note some remarkable and daring lay-outs, which however appear rationally based, providing several amenities". Boffrand's pavilion of 1712–15 that inaugurated the new quarter of the Faubourg Saint-Honoré was purchased and became the Hôtel de Duras.