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.
GlaxoSmithKline sues Pfizer, BioNTech over COVID vaccine technology
GlaxoSmithKline sued Pfizer and BioNTech in Delaware federal court on Thursday, accusing them of infringing GSK patents related to messenger RNA (mRNA) technology in the companies' blockbuster COVID-19 vaccines.
Israel says it is poised to move on Rafah
Israel's military is poised to evacuate Palestinian civilians from Rafah and assault Hamas hold-outs in the southern Gaza Strip city, a senior Israeli defence official said, despite international warnings of a humanitarian catastrophe.
China evacuates entire town as record rains, winds lash its south
Relentless rains, hail and winds of near hurricane intensity battered southern China, forcing the evacuation of an entire town of more than 1,700 people in the province of Guangdong, media said on Thursday.
More than 100 pilot whales stranded in Western Australia, experts say
Marine wildlife experts were frantically trying to rescue some 140 pilot whales stranded on Thursday in the shallow waters of an estuary in the southwest of the state of Western Australia.
Grand jury indicts 18 in Arizona fake elector scheme
A grand jury has charged 18 people with allegedly participating in an Arizona fake elector scheme to re-elect then-US President Donald Trump in 2020, the state's attorney general said on Wednesday.
10:00pm - Midnight
Direct from Hollywood - get ready for some fun from Seacrest and the biggest stars that join him.
10:00pm - Midnight
BRED Abu Dhabi, Presented by Hypebeast, is back April 24-28 in Yas Bay. The line up is next level and locked in.
Not in the car so much while Kris, Priti and Rossi are on air? Check out the daily podcast here...
The super-star and multi-award-winning singer-songwriter, Jason Derulo is bringing the heat to Dubai.
It arrived: The UAE's First Mega Music Festival at Expo City Dubai!
