Turner was born in Wanstead, Essex and grew up in London. He was educated at Bancroft's School. In 1967, he went to Belfast and enrolled at the Queen's University of Belfast where he read geography. Turner was the first member of his family to go to university. Returning to London for his first Christmas break from college, he learned that one of his grandmothers was born on the Falls Road in Belfast, thus qualifying him for Irish nationality and an Irish passport.
Around 1970, he began drawing professionally for the Sunday News. Upon graduation, he joined the Belfast current affairs magazine Fortnight, where he became assistant editor, editor and then co-editor with Tom Hadden. In 1976 he was made political cartoonist at the Irish Times, where he still draws 4 cartoons a week and writes occasionally.
The Cartoonists and Writers Syndicate/New York Times distribute some of Turner's cartoons to over 200 journals and newspapers round the world.
He has also worked for various British publications such as The Scotsman, Business AM, The Business, The Sunday Express, The Independent, the Guardian and The Spectator and the Paris-based current affairs magazine Courrier International.
Turner lives in County Kildare with his wife. He has one son and two grandsons.
Turner was named:
- 1997, commentator of the Year, Irish Media Awards
- 2001, European Political Cartoonist of the Year, Forte dei Marmi
- 1998, awarded an honorary doctorate by the University of Ulster
- 2001, awarded an honorary doctorate by Queen's University Belfast
- 2010 Canadian Human Rights Awards
- 2010 Tonight Media Awards, Dublin
- "Turner's Taoisigh – My Brush With Kildare Street" (Irish Times books 2014)
- "Our Work Here Is Done" (Irish Times Books 2011)ISBN 9780907011354
- Up Every Tree- The bumper Book of Bertie (Gill and Macmillan – October 2006) ISBN 0-7171-4158-6
- Martyn Turner's Greatest Hits (Gill & Macmillan – 28 October 2003) ISBN 0-7171-3573-X
- Railings (Blackstaff Press – October 2000) ISBN 0-85640-687-2
- The Golfer's Guide to World History (Blackstaff Press – November 1999) ISBN 0-85640-663-5
- Brace Yourself, Bridge It! (Blackstaff Press – October 1998) ISBN 0-85640-639-2
- The Noble Art of Politics (Blackstaff Press – October 1996) ISBN 0-85640-583-3
- Pack Up Your Troubles (Blackstaff Press – September 1995) ISBN 0-85640-569-8
- The Odd Couple (Irish Times Books – November 1994) ISBN 0-907011-21-7
- Politics et al. (Irish Times Books – 1992) ISBN B0000COI18
- The Long Goodbye: A cartoon tribute to a Taoiseach (Irish Times Books – 1992) ISBN 0-907011-19-5
- The Man Who Won the Tour De France (Gill & Macmillan-31 October 1991) ISBN 0-7171-1916-5
- Not Viking Likely (Irish Life Viking Adventure 1988)
- Heavy Weather (Gill & Macmillan – 31 December 1989) ISBN 0-7171-1699-9
- Fistful of Dáilers (Gill & Macmillan – 20 October 1987) ISBN 0-7171-1551-8
- 'Illuminations' (Boethius Press 1986)
- Martyn Turner: The Book (Irish Times Books – 1983) ISBN 0-907011-10-1
In 2007,2008,2009,2010 and 2011 The Irish Times published a calendar of Turner cartoons, given away free with the newspaper
- Thin Black Lines Rides Again – Colm Regan, Scott Sinclair, Martyn Turner (TIDE – June 1994) ISBN 0-948838-30-2
- Cattle Rustling: A Retelling of the Táin – James Simmons, Martyn Turner (Fortnight Educational – December 1991) ISBN 0-9509081-3-4
- Thin Black Lines – Colm Regan, Scott Sinclair
- Columba – A cartoon History of The Americas (Potatoe Press)
- Pull the Door Marked Push: Inside the High I. Q. Society – Anne Schulman (Granta Editions, Nov 1992) ISBN 0-906782-96-1
- Last Sunday's Martyn Turner cartoon. (The Irish Times is not published on a Sunday.)
- Biography at the British Cartoon Archive