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.
Omani navy rescues cargo ship crew after missile strike
The Royal Navy of Oman has rescued all 24 crew members of a cargo ship after the Malta-flagged vessel was reportedly struck by two missiles near the Strait of Hormuz.
UN 'deeply disturbed' by strike on Iran school that killed 160 children
A United Nations panel of experts said on Wednesday it was "deeply disturbed" by the deaths of children, after the bombing of the Shajareh Tayyebeh girls' school in southern Iran, which it said killed more than 160 children, citing reports.
Saudi confirms attempted attack on oil refinery, no damage
Saudi Arabia's Ministry of Energy has confirmed that the drone attack on Ras Tanura refinery on Wednesday morning did not cause any damages.
At least four killed in Israeli strike on building in Lebanon's Baalbek
An Israeli strike on a four-storey residential building has killed at least four people and wounded six others in the eastern Lebanese city of Baalbek, with rescue teams working to pull families from beneath the rubble, state news agency NNA said on Wednesday.
Kuwait announces death of child from shrapnel wound
An 11-year-old girl has died of injuries sustained from falling shrapnel on a residential area in Kuwait, the country's Ministry of Health announced early Wednesday.
The UAE is exempting fines for travellers unable to depart due to recent flight suspensions and airspace closures.
The UAE Ministry of Education and Ministry of Higher Education and Scientific Research has announced early closure for spring break for all public and private schools, as well as universities.
All Etihad Airways scheduled commercial flights to and from Abu Dhabi are suspended until 6:00 AM UAE time on Friday, March 6.
