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.
British PM Starmer to send four Typhoon jets to Qatar
British Prime Minister Keir Starmer said on Thursday that four additional Typhoon fighter jets would be sent to Qatar amid the ongoing regional developments, insisting that the UK has the right plan for defence.
Bombing of Tehran intensifies as war enters day six
The US-Israeli campaign against Iran entered its sixth day on Thursday with what residents described as even more intensive bombing.
Azerbaijan vows to respond after four injured by Iranian drones
Azerbaijan warned on Thursday that it was preparing unspecified response measures after a pair of Iranian drones flew across its border and injured four people in the Nakhchivan exclave, raising concern about further spillover of the conflict in the Middle East.
72 killed in Israeli attacks on Lebanon as it warns residents to leave south
Israel has warned residents to immediately leave a swathe of south Lebanon on Wednesday, ordering them to move north of Litani River on the third day of full-blown hostilities with Hezbollah, with the death toll rising to 72 people.
Latest With Hit
Akhil Kavalayoor live on Radio Active
Latest With Hit
Watch Dona & Jean as they grove to SakkathaGavle !
Latest With Hit
Ted X speaker, AI trainer Raul John Aju giving us AI lessons.
