Ukraine's parliament elected its speaker, Volodymyr Groysman, to the post of prime minister on Thursday, state news agency Ukrinform reported.
Groysman's deputy, Andriy Parubiy, is likely to succeed him as speaker.
The parliament on Thursday also approved the resignation of outgoing prime minister, Arseniy Yatsenyuk, who stepped down amid widespread allegations of corruption in the government.
Groysman said in a videotaped announcement this week that his cabinet of ministers "will absolutely not tolerate any corruption."
Groysman is a reputed close ally of President Petro Poroshenko and initially expressed doubts about assuming the premiership, Ukrinform reported.
Poroshenko, who amassed a fortune in the chocolate business before becoming president in 2014, has fallen out of favour with many Ukrainians who believe he has failed to weed out corruption among the country's governing elite.
US Vice President Joe Biden congratulated Groysman in a phone call Thursday.
Biden stressed that in order to maintain international support, Ukraine "should move forward quickly" on its reform programme, including fulfilling its IMF commitments, implementing the Minsk agreement and confirming a new, reformist prosecutor general, according to a White House statement.
Kiev was plunged into political uncertainty in February when the pro-Western coalition lost its legislative majority in parliament, prompting fears of further instability as it continues to grapple with a pro-Russian separatist rebellion in its two eastern-most regions.
Relations with neighbouring Russia have plummeted to an all-time low since Kiev ousted its pro-Russian president in 2014. Moscow responded by annexing Ukraine's southern Crimea region and supporting the then-erupting rebellion in the east.
The European Union this week urged Kiev to "very rapidly" form a new government.
A spokeswoman for EU foreign policy chief Federica Mogherini, Maja Kocijancic, pointed to the need to press ahead with political and economic reforms, as well as the implementation of a peace deal for eastern Ukraine.