The Third Canadian Ministry was the second cabinet chaired by Prime Minister John A. Macdonald.

It governed Canada from 17 October 1878 to 6 June 1891, including the 4th, 5th, and 6th Canadian Parliaments, as well as the first three months of the 7th.

The government was formed by the Liberal-Conservative Party in coalition with the old Conservative Party of Canada.

Macdonald was also Prime Minister in the First Canadian Ministry.