Although in November 1939 he became a member of the Czechoslovak National Committee founded by Beneš, and in July 1940 Osuský was designated a minister of the Czechoslovak government in exile in London, his relations with Beneš were deteriorating.
V novembri 1939 sa síce stal členom Československého národného výboru, ktorý založil Beneš, a v júli 1940 bol vymenovaný za ministra česko-slovenskej exilovej vlády v Londýne, ale vzťahy s Benešom sa zhoršovali.