The Third Hughes ministry (Nationalist) was the 13th ministry of the Government of Australia. It was led by the country's 7th Prime Minister, Billy Hughes. The Third Hughes ministry succeeded the Second Hughes ministry, which dissolved on 17 February 1917 after the governing National Labor Party merged with the Liberal Party to form the Nationalist Party. The National Labor Party itself formed as a consequence of the split that took place within the then-governing Labor Party over the issue of conscription. The ministry was replaced by the Fourth Hughes ministry on 8 January 1918 following the resignation of Hughes as Prime Minister after a vote of no-confidence within the Nationalist Party in the wake of a failed second referendum on conscription. However, due to a lack of alternative leaders, Hughes was immediately re-commissioned as Prime Minister by Governor-General Sir Ronald Munro Ferguson.

The Nationalist Party, also known as the National Party, was an Australian political party. It was formed in February 1917 from a merger between the Liberal Party and the National Labor Party, the latter formed by Prime Minister Billy Hughes and his supporters after the 1916 Labor Party split over World War I conscription. The Nationalist Party was established as a 'united' non-Labor opposition that had remained a political trend once the Labor party established itself in federal politics. The party was in government until electoral defeat in 1929. From that time it was the main opposition to the Labor Party until it merged with pro-Joseph Lyons Labor defectors to form the United Australia Party (UAP) in 1931. The party is a direct ancestor of the Liberal Party of Australia, the main centre-right party in Australia.