It follows reports that President Trump was outraged by comments made by Mulvaney during the Ukraine corruption saga.
The allegations of abuse of power over the Ukraine incident led to impeachment proceedings against President Trump.
Mulvaney's departure has been on the cards for the last few weeks.
Mr Mulvaney is to become US special envoy to Northern Ireland, while North Carolina lawmaker Mark Meadows has been appointed to take over his former position.
Trump says US, Israel to hold off on fresh Iran attack in hope of quick deal
US President Donald Trump said late on Saturday he would hold off on a fresh attack on Iran as long as a deal could be reached quickly to halt Iran's nuclear ambitions and reopen the Strait of Hormuz.
Israeli strikes kill two in Gaza, destroy medicine storage warehouses
Israel's military on Saturday killed two Palestinians in Gaza and destroyed two warehouses near a hospital that stored medicine in separate strikes, amid uncertainty over whether Israel has accepted a deal reached with Hamas over the group's disarmament.
Thirteen die in tourist plane crash over Peru's Nazca Lines
A small tourist plane crashed on Saturday as it flew over the Nazca Lines archaeological site in southern Peru, killing 13 people, Peru's government said.
Bomb carried by woman kills three, injures 21 near Moscow restaurant, authorities say
A homemade bomb carried by a woman killed three people and injured at least 21 in an explosion near an upscale restaurant in central Moscow on Saturday evening, the authorities said.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan held talks with Ukrainian President Volodymyr Zelenskyy on Sunday, focusing on bilateral cooperation and the latest developments in the Ukraine conflict.
His Highness Sheikh Hamdan bin Mohammed bin Rashid Al Maktoum, Crown Prince of Dubai, Deputy Prime Minister and Minister of Defence of the UAE, has approved the formation of the Supervisory Committee for Initiatives under the ‘Sheikha Hind bint Maktoum Family Programme’.
The Roads and Transport Authority (RTA) has announced that 348.1 million people used public transport, taxis and shared mobility in Dubai in the first half of 2026.
