The Johnson ministry was established part-way through the 21st Parliament of British Columbia, after John Hart resigned as premier and leader of the Liberal Party.

Johnson was elected as the Liberal Party's new leader at the party's 1947 convention, and outgoing premier Hart pledged to recommend Johnson to the lieutenant governor of British Columbia to be the province's next premier.

[1] However, the Hart ministry had been a coalition between the Liberal and Conservative parties, and in the immediate aftermath of Johnson's leadership victory, it was uncertain if the two parties would renew their coalition arrangement.

Johnson and Herbert Anscomb, leader of the Conservatives, agreed to continue the coalition on December 27, 1947.

For the last six months of the 22nd Parliament, the Johnson ministry continued as a minority government, consisting only of Liberal ministers but supported by a few independent members.