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.
US, India agree on trade deal and lower tariffs, says Trump
US President Donald Trump on Monday said he had agreed on a trade deal with India that slashes tariffs on Indian goods to 18 per cent in exchange for India lowering trade barriers, stopping its purchases of Russian oil and buying oil instead from the US and potentially Venezuela.
Israel reopens Gaza's Rafah border crossing to Egypt, with limits
Israel reopened the border between Gaza and Egypt on Monday for people on foot, a move that would allow Palestinians to leave the enclave and let back in those who want to return after fleeing Israel's war in the enclave.
US envoy Witkoff to visit Israel, meet Netanyahu, Israeli officials say
US President Donald Trump's senior envoy Steve Witkoff is expected to visit Israel for meetings with Prime Minister Benjamin Netanyahu and Israel's military chief, two senior Israeli officials said on Monday.
Russian drone strike kills 12 miners in Ukraine
At least 12 people were killed and seven wounded after a Russian drone struck a bus carrying miners in Ukraine's southeastern Dnipropetrovsk region, energy firm DTEK and government officials said on Sunday.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan has led messages welcoming guests to the World Government Summit 2026, running from February 3 - 5 under the theme ‘Shaping Future Governments’.
The UAE has denied false and unfounded claims that it would assume civilian administration of Gaza.
His Highness Sheikh Mohammed bin Rashid Al Maktoum, Vice President and Prime Minister of the UAE and Ruler of Dubai, has explored ways to strengthen cooperation with Kristalina Georgieva, Managing Director of the International Monetary Fund (IMF), at the World Governments Summit on Monday.
