[2] He served as a U.S. Foreign Service Officer from 1921 to 1953, and his career included posts in Europe, Latin America, and the United Nations.

He served as Envoy Extraordinary and Minister Plenipotentiary to Sweden between 12 December 1941 and 28 April 1946.

During his time in Sweden, he made humanitarian efforts to save civilian lives and was in touch with Raoul Wallenberg.

The outcome of the UN vote is attributed to his collaboration with Andrei A. Gromyko, otherwise Johnson's political opponent.

They both stood together on this issue and urged the General Assembly not to delay its decision but to vote for partition at once, opposing last-minute efforts of Arab delegations to effect a compromise.