News Ltd, owner of The Australian, made the shift after being impressed by a number of projects that it handed to Brave over the past year.
The weekend edition of the newspaper had already switched its creative duties from Clemenger to Brave in September last year.
Clemenger will continue to be considered for work on a project-by-project basis.
Peter Malycon, the managing partner at Brave, said: "We consider The Australian to be our flagship brand. It's an iconic product."