Speaking at a media conference in Sydney, Truss was asked if she supported Johnson and whether she would run for leader of the Conservative Party if a contest was called.
"The Prime Minister has my 100% support," said Truss. "I want the Prime Minister to continue as long as possible in his job. He is doing a fantastic job. There is no leadership election."
Truss has been tipped as a possible replacement for Johnson who has been rocked by scandals over parties at No. 10 held during strict national lockdowns.