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 text of signed US, Iran deal will be released on Friday
US President Donald Trump said on Monday a deal with Iran has been agreed and the text of the deal will be released sometime after the formal signing in Switzerland on Friday.
Lebanon fighting eases after US-Iran deal but displaced warned not to rush home
Fighting in southern Lebanon eased on Monday after the US-Iran deal to end the wider conflict was announced, but an Israeli drone strike killed one person and authorities warned displaced people not to rush home as Israel said it would keep troops in the south.
Ukrainian man found guilty of setting on fire houses linked to UK PM Starmer
A Ukrainian man was found guilty on Monday of carrying out arson attacks on property connected to British Prime Minister Keir Starmer in May last year on behalf of a mystery figure he knew only as "EL Money".
Britain announces sweeping social media ban for under-16s
British Prime Minister Keir Starmer said on Monday he would ban social media sites for under-16s and impose restrictions on gaming and live-streaming platforms, in a fightback against big tech that goes further than any other country.
The UAE reiterated the importance of dialogue, diplomacy and adherence to international law following the US-Iran memorandum of understanding.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan will attend the 52nd G7 Summit, which will take place between June 15 and June 17.
United Arab Emirates President His Highness Sheikh Mohamed bin Zayed Al Nahyan travelled to Egypt on Monday to speak with President Abdel Fattah El-Sisi.
