Whilst at Oxford University in the 1970s, he briefly played bass in the band Ugly Rumours alongside Tony Blair. A band, which according to Ellen existed primarily to meet "exciting girls in floral print dresses" 
After graduating, he wrote for Record Mirror, NME and Time Out before signing up as Features Editor of Smash Hits in 1981, where he became the editor in 1983. He was the launch editor of Q, the re-launch editor of Select, and the launch managing editor of Mojo. He later became the editor-in-chief of EMAP Metro overseeing 14 consumer magazines but he left Emap after 16 years to join the independent publishing company Development Hell in 2002.
He also has a long broadcasting career which includes contributions to BBC Radio 1 as stand-ins for David "Kid" Jensen and John Peel. He presented the BBC's Whistle Test from 1982-1987. He also co-presented the Live Aid TV broadcast in 1985.
Ellen was the editor of The Word, a UK music magazine which he started with long-time colleague, business partner and Whistle Test co-presenter David Hepworth. The first issue was published in February 2003 and the magazine celebrated its 50th issue in March 2007. The closure of the magazine was announced in June 2012.
His awards include the PPA's Magazine Of The Year for Q and the British Society Of Magazine Editors' special Mark Boxer Award in 2003. He won also the BSME's Editor's Editor Award in 2005  and again in 2011.
- "He even wanted to rehearse" The Guardian, 27 April 2003
- Insidious Albion | By genre | guardian.co.uk Books
- Sony Radio Academy Awards - Judges : Mark Ellen
- Word magazine: A bunch of friends and a record player - Media, News - The Independent
- screenonline: Old Grey Whistle Test, The / Whistle Test (1971-87)
- Live Aid (July 13th, 1985) : MARK ELLEN
- Ruth Addicott, "Word magazine cover unveiled", Press Gazette, 31 January 2003
- "Word magazine: A bunch of friends and a record player", Independent (UK), 12 March 2007
- Word Magazine - Rejoice, readers of The Word!
- Press Gazette - Mark Ellen wins top editors' award
- Divernet | Jordan | No desert underwater
- Blessed in cyclists' heaven - Telegraph