Former international development minister Stephen O'Brien has been appointed as the new aid chief at the United Nations.
UN secretary general Ban Ki-moon announced the Conservative would replace L abour former Cabinet minister Baroness Amos, who announced she was stepping down last November, as the under secretary general for humanitarian affairs.
The MP will bring "e xtensive experience in multilateral diplomacy" and "international leadership and management" to the top job, the UN said.
But global campaign group Avaaz criticised the appointment as a victory for "political patronage over meritocracy".
The high-profile post of under secretary general for humanitarian affairs and emergency relief coordinator has been held by a British representative since 2007.
Avaaz campaign director Sam Barratt said: "Of the three names put forward by Britain, Stephen O'Brien was the best candidate.
"But with a world of humanitarian experts to chose from, this appointment shows the carve up of senior UN jobs is still based on the colour of passports, not the quality of CVs. For the good of the world, this old system of political patronage over meritocracy has to come to an end."
Mr O'Brien, who is standing down as MP for Eddisbury, has been Prime Minister David Cameron 's special representative for the Sahel region of Africa.
Former cabinet minister Andrew Lansley's name was linked with the position but critics raised concerns over his lack of experience of humanitarian work.
The UN has previously insisted that the role is not reserved for an individual from any one member nation.
Mr Lansley made clear his desire for a top job away from Westminster in the letter he wrote to the Prime Minister when he was removed as Commons leader in last year's reshuffle thanking him for supporting his desire to take a ''challenging and important'' international post.
The PM replied that Mr Lansley, his former boss in the Conservative Party research unit who oversaw highly-controversial NHS reforms as health secretary, had ''much more to give in terms of public service, and I look forward to being able to support you in doing so in the months and years ahead''.
When the vacancy opened up Mr Lansley's office said: ''There will be a UN recruitment process and he would not wish to pre-empt that or take it for granted."