As has become his habit, Mr Trump announced the news on Twitter, saying that the position was to be filled by former general John Kelly, the man who is currently the Secretary of the Department of Homeland Security. It emerged that Mr Priebus, 45, had offered his resignation the day before, following a public spat with Mr Trump's new Director of Communications, Anthony Scaramucci.
“I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff. He is a Great American and a Great Leader. John has also done a spectacular job at Homeland Security. He has been a true star of my Administration,” Mr Trump said on Twitter.
“I would like to thank Reince Priebus for his service and dedication to his country. We accomplished a lot together and I am proud of him.”
After Mr Trump had broken the news on social media - apparently as he was flying back from an appearance on New York's Long Island where he was accompanied by Mr Priebus - he spoke briefing with travelling reporters. “Reince is a good man. John Kelly will do a fantastic job,“ he said. ”General Kelly has been a star, done an incredible job thus far, respected by everybody. He's a great great American. Reince is a good man.”
In truth, Mr Trump had long been suspicious and disappointed with Mr Priebus, and there had been speculation about him being ousted almost since he took the job earlier this year - having moved over from the Republican National Committee where he was chairman.
There are turf wars in every White House, with different factions seeking leverage and advantage. Yet Mr Trump appears to have actively encouraged such chaos and competitiveness within his administration - believing that such a system had worked for him in business. Indeed, in the six months that Mr Trump has occupied the Oval Office, various figures have seen their fortunes rise and fall, among them advisor Steve Bannon, Jeff Sessions, and Mr Priebus himself.
But while many were expecting that Mr Sessions would resign as Mr Trump continued to criticise his decision to recuse himself from the investigation into Russia, in the last 24 hours it emerged that Mr Priebus had become very vulnerable.
On Thursday night, in a bizarre interview with New Yorker reporter Ryan Lizza, Anthony Scaramucci, Mr Trump’s new Director of Communications, said that Mr Priebus would not last much longer.
At one point during the call, Mr Scaramucci called Mr Priebus a “f***ing paranoid schizophrenic”. He also accused Mr Priebus of being behind the flow of damaging leaks about the White House and said he was going to ask the FBI to investigate him.
That interview was not published until Thursday. In the intervening hours, Mr Scaramucci sought to suggest he and Mr Priebus were like brothers.
“When I said we were brothers from the podium, that’s because we're rough on each other - some brothers are like Cain and Abel,” he said to CNN, referencing a biblical passage that ends in Cain killing Abel. “Other brothers can fight with each other and then get along. I don’t know if this is repairable or not. That will be up to the president.”
The enmity between Mr Scaramucci and Mr goes back some time. Mr Scaramucci was to to have taken up a senior White House role in January but he was blocked by the chief-of-staff.
When he did arrive in the West Wing last week - against the advice given to Mr Trump by Mr Priebus and spokesman Sean Spicer, who subsequently quit - it was noted that the brash New Yorker was to report directly to Mr Trump and not Mr Priebus, as would normally have been the case for a communications director.
On Thursday, Mr Spicer's replacement in the White House briefing room, Sarah Huckabee Sanders, would not say whether Mr Priebus still have the confidence of the President. As it is, Mr Kelly will start in his new job on Monday morning. There was no immediate news on who would replace Mr Kelly.
Before the news was announced, Mr Trump had praised Mr Kelly, a former four star general who served three tours in Iraq, during a speech in New York’s Long Island where he was talking about the fight against gang crime.
“I want to congratulate John Kelly, who has done an incredible job of Secretary of Homeland Security,“ he said. ”Incredible. One of our real stars. Truly, one of our stars. John Kelly is one of our great stars.“
Mr Priebus insisted he had resigned, and had not been fired.
“The President wanted to go in a different direction,” Priebus told CNN.
“I think General Kelly is a brilliant pick. We'll be working on a transition here for a couple weeks together with General Kelly starting on Monday morning.
“So this is not like a situation where there are a bunch of ill will feelings. I'm always going to be a Trump fan,” Mr Priebus added.