Zec's career in journalism began in 1938 with a three-day trial at the Daily Mirror. He has recalled: "I was so embarrassingly bad that no one had the courage to tell me, so I stayed for 40 years." During the war, he served in the London Irish Rifles, returning to the Daily Mirror as a crime reporter.
On one occasion, he interviewed the infamous acid-bath murderer John George Haigh in the Onslow Court Hotel.
He subsequently became the paper's Royal correspondent and then film writer. In the course of his work he interviewed and wrote about many celebrities, particularly from the worlds of entertainment and showbusiness, including Humphrey Bogart, Brigitte Bardot, David Niven, Ingrid Bergman, The Beatles, and Marilyn Monroe.
In October 1967 he won a National Press Award as Descriptive Writer of the year, the citation spoke of his 'bland outrageousness and a deadly certainty of aim..' Extending his range, he interviewed major political figures such as a former Chancellor of the Exchequer Selwyn Lloyd, the late Labour Prime Minister, Harold Wilson, the (then) leader of the Opposition Margaret Thatcher. the late Lord Mountbatten of Burma and the former Californian Governor Ronald Reagan in 1967, commenting; 'it is a whimsical if not uneasy thought that an ex-movie star of many films that escape instant recollection could one day become President of the United States of America ' In 1970 he was awarded the OBE for services to Journalism.
In October 2012 he won the Oldie Magazine's inaugural British Artists Award (OBA) for artists over the age of sixty. A year later his portrait of his late paternal grandfather was prsented at the Royal Academy Summer Exhibition,jointly winning the Hugh Casson Prize for Drawing.
- Barbra: A Biography of Barbra Streisand (with Anthony Fowles). London: Hodder, 1982; ISBN 0-450-05398-9 (softcover) / ISBN 0-450-04857-8 (hardcover). New York: St Martin's Press, 1981; ISBN 0-312-06638-4
- The Colonel - a novel. London: Virgin Books, 1980; ISBN 0-352-30537-1 (softcover). W.H. Allen; ISBN 0-491-02376-6 (hardcover)
- The Deal. London: Hodder, 1980; ISBN 0-450-04411-4 (softcover) / ISBN 0-450-04030-5 (hardcover)
- Don't Lose It Again! The Life and Wartime Cartoons of Philip Zec. London: Political Cartoon Society, 2005; ISBN 0-9549008-1-2
- The Face. London: Political Cartoon Society, 1981; ISBN 0-450-04752-0 (hardcover)/ ISBN 0-450-05226-5 (softcover)
- Liz: The Men, the Myths, and the Miracle - An Intimate Portrait of Elizabeth Taylor. Bookman Projects, 1982; ISBN 0-85939-316-X
- Marvin: The Story of Lee Marvin. London: Hodder, 1980; ISBN 0-450-04115-8. New York: St Martin's Press; ISBN 0-312-51780-7
- Put the Knife in Gently: Memoirs of a Life with Legends. London: Anova Books, 2003; ISBN 1-86105-697-4
- The Queen Mother: With Unique Recollections by the Earl Mountbatten of Burma. Thorndike Press, 1990: ISBN 0-86220-417-8
- Sophia: An Intimate Biography. London: W.H. Allen, 1975; ISBN 0-491-01732-4. G.K. Hall; ISBN 0-8161-6379-0
- Some Enchanted Egos: Decent Exposures of Some of the Most celebrated Characters of Our Time. London: Allison & Busby, 1972; ISBN 0-85031-078-4
- This Show Business, Donald Zec on. London: Daily Mirror, 1959.
- When the Snow Melts: The Autobiography of Cubby Broccoli (with Albert R. Broccoli). London: PanMacmillan, 1999; ISBN 0-7522-1162-5 (hardcover) / ISBN 0-7522-1704-6 (softcover)
- Noble, Peter (1970). British film and television year book. Cinema TV Today. p. 394.
- Bill Hagerty, "Fame that won't live forever", Press Gazette, 14 March 2003.
- Michael Freedland "Donald Zec: He scooped them all…", The Jewish Chronicl, 26 March 2009. accessed 26 February 2012.
- "Donld Zec's Celebrity Scrapbook", The Jewish Chronicle Online, 24 March 2009.
- "Donald Zec and Marilyn", EverlastingStar.net, 1 February 2012.
- L.A. Times, "Beautiful Snob" - July 22, 1973
- History Today, May 18 2005.
- Review by Dr Bex Lewis (2005-6)