Foreign Secretary is seen as a hopeful to replace the outgoing prime minister
De foreign secretary said the prime minister had “made the right decision” by quitting.
Ms Truss was on a trip abroad visiting Indonesia while Mr Johnson’s cabinet collapsed around him and had so far not spoken publicly about the turmoil in Westminster.
She is widely seen as a potential leadership hopeful to replace the prime minister.
“The PM has made the right decision,” she said in a message posted on social media.
“The Government under Boris’s leadership had many achievements – delivering Brexit, vaccines and backing Ukraine.
“We need calmness and unity now and to keep governing while a new leader is found.”
Though Ms Truss had not publicly commented on the situation in Westminster she had made clear through sources close to her that she was standing by the prime minister.
On Thursday Mr Johnson announced he would be stepping down as Tory leader and prime minister when a successor had been found.
But some Conservatives and opposition politicians believe he should go immediately given the nature of his departure.
Over MPs quit government roles over the last 36 hours in a bid to force him out. Mr Johnson had been criticised for his handling of an alleged case of sexual abuse by one of his senior MPs.