Cornwell worked in advertising following graduation. He began his career in journalism with Reuters in 1968. Cornwell was sent to the Brussels branch office, where he met his first wife, interpreter Angela Doria. They moved to Paris, where Cornwell joined the Financial Times as a foreign correspondent. From France, Cornwell and Doria moved to Rome, and Bonn.[4] Cornwell was the first Moscow correspondent of The Independent, from its launch in 1986.[5] During this time, he won two British Press Awards. Later in his career, Cornwell served as the Chief US Commentator at The Independent newspaper.
His first marriage, in 1972, was to European Parliament interpreter Angela Doria; they had a son, Sean (born 1974).[7] In 1988, he married Susan Smith, whom he had met while in Bonn.[4] They had a son, Stas.[2]