On his return to the Netherlands, Van Campen turned to architecture, applying ideas borrowed from Andrea Palladio, Vincenzo Scamozzi, and classical influences from Vitruvius.

He was assisted in his work by Pieter Post, Daniël Stalpaert, Matthias Withoos, Philips Vingboons, Artus Quellinus, Tielman van Gameren and Rombout Verhulst.

During the building of the city hall, Van Campen lived in very expensive lodgings in the nearby Kalverstraat and he spent freely.

After a long career, Van Campen died in 1657 in his buitenplaats (residence) Randenbroek near Amersfoort, which he had inherited from his mother, and was buried there.

His paintings and wall decorations (such as those at Paleis Huis ten Bosch), show some similarity with the work of Paulus Bor, one of the founders of a group of painters calling themselves the Bentvueghels.