De Block worked as Chief executive officer (CEO) of the Incasso Bank from July 1946 until February 1947.

After the election of 1963 De Block was appointed as State Secretary for Foreign Affairs in the Cabinet Marijnen, taking office on 3 September 1963.

The Cabinet Cals fell on 14 October 1966 after the Leader of the Catholic People's Party Norbert Schmelzer had proposed a motion that called for a stronger austerity policy to further reduce the deficit was seen an indirect motion of no confidence and continued to serve in a demissionary capacity until the cabinet formation of 1966 when it was replaced by the caretaker Cabinet Zijlstra with De Block remaining State Secretary for Foreign Affairs and also appointed as State Secretary for Transport and Water Management and dual served in those positions, taking office on 22 November 1966.

[1] On 7 January 1970 De Block resigned after he disagreed with the cabinets decision to increase the wages in the metal industry but another reason was criticism on his leadership in the handling of the rising inflation after the introduction of the value-added tax (BTW).

[2] De Block semi-retired from in national politics and became active in the private sector and public sector and occupied numerous seats as a corporate director and nonprofit director on several boards of directors and supervisory boards (DSM Company, ING Group, Robeco and Van Lanschot) and served on several state commissions and councils on behalf of the government (Cadastre Agency, Dutch Transport Safety Board and the Advisory Council for Foreign Affairs).