McKell had planned to retire from public life in 1946, but was instead convinced by Ben Chifley to become governor-general. His appointment was initially controversial due to its openly political nature; Robert Menzies called it "shocking and humiliating". However, when Menzies returned as prime minister in 1949 they formed an amicable working relationship. Some of McKell's actions as governor-general were unpopular amongst his old Labor Party colleagues, notably his acceptance of a knighthood and his decision to grant Menzies a double dissolution in 1951. In later life, he served as a trustee of the Sydney Cricket Ground and as a member of the Reid Commission, which drafted the Constitution of Malaysia.