Stephen Barclay has been confirmed as the new Brexit Secretary as Theresa May seeks to fill posts in her cabinet.
The MP for North East Cambridgeshire and Leave supporter had been serving as a minister at the department for health and social care.
He replaces Dominic Raab, who resigned on Thursday over Mrs May’s withdrawal agreement for Brexit.
A spokesman for No 10 indicated that Mr Barclay would focus on the domestic preparations rather than negotiations.
Labour’s shadow Brexit secretary Sir Keir Starmer said: “Stephen Barclay’s appointment changes absolutely nothing.
“After two years of negotiation, the prime minister has failed to deliver a Brexit deal that can command the support of Parliament.
“A new face in the Brexit department will do nothing to bring this divided government back together.”
The announcement comes after Amber Rudd was named the new work and pensions secretary – replacing Esther McVey, who also resigned over the PM’s Brexit plans on Thursday.
Ms Rudd said she was “delighted” to be given the role, and saw it as her job to “try to iron out” the issues with Universal Credit.
Stephen Hammond will take over from Mr Barclay at the department for health and social care.
The government also announced replacements for two junior ministers who resigned over Mrs May’s deal.
John Penrose will join the Northern Ireland office, replacing Shailesh Vara, and Kwasi Kwarteng will go to the Department for Exiting the EU, replacing Suella Braverman.
Mr Barclay – a former banker – has also held the posts of City minister and a whip at the Treasury.
BBC assistant political editor Norman Smith said he was not a household name and it was a big promotion for him.
But he also described Mr Barclay as ultra-loyal, having never rebelled against the government.
Environment Secretary Michael Gove is understood to have turned down the role of Brexit secretary following Mr Raab’s departure.
Mr Barclay becomes the third Brexit Secretary since the role was created, after Mr Raab and David Davis – who resigned over Mrs May’s Brexit plans in July.
He has been congratulated on Twitter by Chief Secretary to the Treasury Liz Truss, who said he was “a star” when he worked in her department.
Mrs May agreed a draft withdrawal agreement for Brexit with her cabinet on Wednesday, which had already been signed off by negotiators from both the UK and EU.
But it led to a backlash from some Brexit-supporting MPs, including Mr Raab and Ms McVey.
Around 20 Tory MPs have publicly called for a vote of no confidence in the prime minister, with more thought to have written to the chairman of the backbench 1922 Committee to call for a vote on her leadership.
But Mrs May responded to critics saying she will stay in No 10 and see the deal through.
Ms Rudd called on her colleagues to “think again” about sending letters against the PM, saying her deal was a “practical response to leaving the European Union.”
She added: “This is not a time for changing our leader. This is a time for pulling together, for making sure we remember who we are here to serve, who we are here to help – the whole of the country.”