Adel Abdul Mahdi, a former oil minister, was picked by Iraq’s newly elected president to head the government.
Mr Abdul Mahdi, a 76-year-old economist who served as finance minister and vice president in previous administrations, was nominated by president Barham Salih on Tuesday.
Just two hours earlier, Mr Salih, a Kurdish politician, was elected to the largely ceremonial post of president by Iraq's parliament.
Iraqi leaders have struggled to form a government since elections in May, and the new premier will take over amid a wave of unrest over corruption and poor services.
Mr Salih swiftly called on Mr Abdul Mahdi to submit his cabinet for parliamentary approval within 30 days, as is required by the Iraqi constitution.
He faces the daunting tasks of rebuilding much of the country after four years of war with ISIS and balancing foreign relations with Iraq's two major allies – the United States and Iran. Deadly protests last month in Basra also left some government offices and the Iranian consulate burned to the ground.
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He will also be challenged to heal ethnic and sectarian tensions.
The prime minister-designate is not allied with either of the two Shiite-led blocs that each claim to have the most support after the May elections, in which no party won an outright majority.
He will become the first elected prime minister since the fall of Saddam Hussein not to hail from the Shiite Islamist Dawa party.
"The nomination of Mr Adel Abdul Mahdi came after an agreement between the Binaa bloc and the Islah bloc to nominate him via consensus, and not a majority bloc, in order to get past the issue of which is the majority bloc," said Ahmed Al Asadi, Binaa bloc spokesman.
Mr Abdul Mahdi is a trained economist who left Iraq in 1969 for exile in France, where he worked for think tanks and edited magazines in French and Arabic. He is the son of a respected Shiite cleric who was a minister in the era of Iraq's monarchy.
Mr Abdul Mahdi succeeds Dawa’s Haider Al Abadi, who led Iraq from 2014 during its fight against ISIS, gaining western backing. But Mr Abadi lost support as a much-vaunted anti-corruption drive foundered and Iraq’s public services deteriorated.