An ardent Patriot, he began as secretary to Pieter Johan van Berckel, the Dutch Republic's first ambassador to the United States of America, from 26 June 1783 to 8 July 1784.
The Revolution broke out again early in 1795 when Patriots rose up (with French military support led by Pichegru) in all of the United Provinces.
William V, Prince of Orange opted for exile on 19 January, leaving the field open for the Batavian Republic to be set up.
On 27 January 1796 he was elected deputy for Meppel in the first national Batavian assembly and appointed to the committee charged with writing a new constitution.
After France annexed the new kingdom in 1811, De Vos was made deputy for Bouches-de-l'Yssel on the legislative corps of the French Empire.