The Fourth Deakin Ministry was the eighth Australian Commonwealth ministry, and ran from 2 June 1909 to 29 April 1910.

Commonwealth Liberal Party

• Hon Alfred Deakin, MP: Prime Minister (without portfolio)
• Hon Joseph Cook, MP: Minister for Defence
• Rt Hon Sir John Forrest, GCMG MP: Treasurer
• Senator Hon Robert Best: Minister for Trade and Customs
• Hon Littleton Groom, MP: Minister for External Affairs
• Hon Paddy Glynn, MP: Attorney-General
• Hon Sir John Quick, MP: Postmaster-General
• Hon George Fuller, MP: Minister for Home Affairs
• Senator Hon Edward Millen: Vice-President of the Executive Council
• Hon Justin Foxton, MP: Minister without portfolio