The president shared the news in a tweet: "I am pleased to announce that Congressman Mark Meadows will become White House Chief of Staff. I have long known and worked with Mark, and the relationship is a very good one. I want to thank Acting Chief Mick Mulvaney for having served the Administration so well. He will become the United States Special Envoy for Northern Ireland. Thank you!"
Meadows is currently a GOP congressman from North Carolina, representing the state's 11th Congressional District. He has served in that role since 2013 and, as chair of the House Freedom Caucus, was considered one of Trump's closest allies in the House of Representatives.
"It's an honor to be selected by President Trump to serve alongside him and his team," Meadows said in a statement Friday night. "This President and his administration have a long list of incredible victories they've delivered to the country during this first term, with the best yet to come—and I look forward to helping build on that success and staying in the fight for the forgotten men and women of America.
"In particular, I want to recognize my friend Mick Mulvaney," Meadows continued. "Mick is smart, principled, and as tough a fighter you'll find in Washington, D.C. He did a great job leading the President's team through a tremendous period of accomplishment over the last year plus."
There was no announcement whether Mulvaney will continue to serve as director of the Office of Management and Budget, a position he maintained throughout his tenure as acting chief of staff.
Mulvaney was Trump's third chief of staff, replacing retired Gen. John Kelly, who succeeded former Republican National Committee Chair Reince Priebus in July 2017.
Trump announced Mulvaney's appointment as acting chief of staff in a tweet in December 2018, and he assumed the role at the start of 2019.
Mulvaney called the job a "tremendous honor" in a tweet following his appointment, adding, "I look forward to working with the President and the entire team. It's going to be a great 2019!"
He served as chief of staff in an "acting" capacity, despite the fact that the White House chief of staff serves at the pleasure of the president and does not require Senate confirmation. Many of the other cabinet officials appointed by Trump as "acting" require a Senate vote to serve in a permanent capacity.
Mulvaney presided as chief of staff during some of the Trump administration's most turbulent moments, including the impeachment of the president over a scheme to pressure Ukraine into investigating Trump's political rivals by withholding foreign aid.
During an October 2019 press conference, Mulvaney directly involved himself in the impeachment scandal, admitting that there was a "quid pro quo" in Trump's now-infamous July phone call with Ukrainian President Volodymyr Zelenskiy.
"So the demand for an investigation into the Democrats was part of the reason that he ordered you to withhold funding to Ukraine?" asked ABC News Chief White House Correspondent Jonathan Karl.
"Look back to what happened in 2016, certainly was part of the thing that he was worried about in corruption with the nation," Mulvaney said. "And that is absolutely equivalent."
"What you described is a quid pro quo," Karl pressed. "It is: Funding will not flow unless the investigation into the Democrats' server happens as well."
"We do that all the time with foreign policy," Mulvaney answered, further fueling House Democrats' impeachment probe. Mulvaney also told reporters to "get over it. There's going to be political influence in foreign policy."
After the press conference, Mulvaney walked back his statement, saying the press misconstrued what he had said. Less than four days later, he appeared on "Fox News Sunday," completely denying the exchange he had with Karl.
"Why did you say, in that briefing, that President Trump had ordered a quid pro quo that aid to Ukraine depended on investigating the Democrats?" Fox's Chris Wallace asked.
"Again, that's not what I said."
During the same press conference, Mulvaney announced that the 2020 G-7 Summit would be held at the Trump National Doral Miami resort. This immediately sparked concerns on both sides of the aisle about whether this would be in direct violation of the Constitution's Emoluments Clause, because the president would be benefiting from the office. Less than three days later, Trump had to walk back this announcement on Twitter, blaming the "Hostile Media & their Democrat Partners." The 2020 G-7 Summit will now be held at Camp David.
Mulvaney did have some support as acting chief of staff. Conservative leaders released a letter in late October stating he was "the most successful chief of staff" Trump has had.
But news in December that Meadows would be joining the administration in a still-undefined role fueled rumors that he might be a replacement for Mulvaney. Meadows has readily expressed a desire to serve as Trump's chief of staff in the past, but has not elaborated on what role he will ultimately take in the administration.
"This President has accomplished incredible results for the country in just 3 years, and I'm fully committed to staying in the fight with him and his team to build on those successes and deliver on his promises for the years to come," Meadows said in a statement.
As recently as Feb. 7, Trump denied rumors that he would replace Mulvaney with Meadows.
"That was a false report," Trump told reporters. "I have a great relationship with Mick. I have a great relationship with Mark. And it's false."
Prior to joining the Trump administration, Mulvaney spent six years in Congress representing South Carolina's 5th Congressional District. He was a founder of the hardline conservative Freedom Caucus, and pushed for House GOP leaders to shut down the government in 2013 over Obamacare.
Mulvaney unenthusiastically supported Trump's 2016 presidential bid. Just days after being named acting chief of staff, video surfaced of Mulvaney describing then-candidate Trump as a "terrible human being" during a congressional debate that took place days before the election.
"Yes, I'm supporting Donald Trump," Mulvaney said in the clip that quickly went viral. "I'm doing so as enthusiastically as I can, given the fact that I think he's a terrible human being, but the choice on the other side is just as bad."
Days before his tenure as acting chief of staff began, Mulvaney told ABC's Jonathan Karl on "This Week" that he and the president "joked" about the video.
"What's wrong with Washington, DC? People spend a lot more time looking at what people say instead of what they do. I think my actions for the last two years -- in fact, I know they have because I asked the president about this -- he knows that I've been fighting with him to fight for ordinary Americans for the last two years. He likes having me around, and I like working for him," Mulvaney said.
Mulvaney served as director of the Office of Management and Budget for the first two and a half years of the Trump presidency and assumed the role of acting director of the Consumer Financial Protection Bureau in November 2017 following a months-long battle over the position with the agency's No. 2 during the Obama administration.
Mulvaney was replaced at CFPB in December 2018 with a Senate confirmed appointment, but remained OMB director throughout his tenure as acting White House chief of staff.