Following the end of World War II, Queen Wilhelmina ordered the formation of a national unity government to serve in a caretaker capacity until the new election, with Vos appointed as Minister of Commerce and Industry in the Schermerhorn–Drees cabinet, taking office on 25 June 1945.

Vos served as acting Minister of Public Works and Reconstruction from 15 November 1946 until 3 March 1947 following the resignation Johan Ringers.

Vos remained in active in national politics, he served as Chairman of the Labour Party from 5 June 1953 until 23 February 1955.

After the 1960 Senate election, Vos was selected as parliamentary leader of the Labour Party, taking office on 15 November 1960.

He holds the distinction as the first known LGBT member of the House of Representatives and government minister of the Netherlands, this fact was an open secret in Dutch politics at that time.