He previously served as a private secretary to Liam Fox during his time as Defence Secretary.
Mr Ellwood was born in New York, grew up in Germany and Austria, and served with the army’s Royal Green Jackets.
He was stationed in Northern Ireland, Cyprus, Kuwait, Germany and Bosnia.
Writing on Twitter after being appointed, the father-of-two said: “Delighted and honoured to be joining Philip Hammond in the Foreign Office with responsibility for Middle East and North Africa”.
Mr Hammond has replaced William Hague as Foreign Secretary.
