Van Amelsvoort was selected as a Member of the European Parliament and dual served in those positions, taking office on 9 March 1970.

Van Amelsvoort returned as a Member of the House of Representatives after Tiemen Brouwer was appointed as Minister of Agriculture and Fisheries in the Cabinet Den Uyl after the election of 1972, serving from 28 May 1973 until 8 June 1977.

After the election of 1982 Van Amelsvoort was appointed as State Secretary for the Interior in the Cabinet Lubbers I, taking office on 8 November 1982.

After the election of 1989 Van Amelsvoort was again appointed as State Secretary for Finance in the Cabinet Lubbers III, taking office on 7 November 1989.

Then he worked a long time in the banking sector as was a Board Member of the First Chamber of the CSF in which he acted as a spokesman for financial affairs.