Dominic Raab has been appointed Brexit Secretary by Theresa May after David Davis resigned from the government.
Mr Raab, who is currently housing minister, was a prominent Leave campaigner during the 2016 referendum.
Mr Davis quit early on Monday morning, saying Theresa May had “given away too much too easily”.
The 44-year old Mr Raab, a lawyer before becoming an MP in 2010, will now take over day-to-day negotiations with the EU’s Michel Barnier.
He has served in government since after the 2015 election, initially working in the Ministry of Justice before moving to the communities department last May.
Mr Davis said he could not remain in his post as he no longer believed in the plan for the UK’s future relations with the EU backed by the cabinet on Friday.
He said his resignation would make it easier for the UK to resist EU attempts to extract further concessions – but he insisted he was not seeking to underline or challenge the prime minister.