Lamarr was born in the Park South area of Swindon and has three elder sisters. His father is Irish. He passed five O-Levels at Park School (renamed Oakfield School) but dropped out of school at 17 and moved to Harrow, which was the centre of the early 80's British rockabilly revival scene. After his poem "Too Fast to Live, Too Young to Work" was published in 1987, his act developed from poetry to stand-up comedy. He took to performing at The Comedy Store, London in 1985, was spotted on the touring circuit for the launch of Channel 4's The Big Breakfast in 1992 and co-presented The Word.

Lamarr first came to the public's attention as a co-presenter of the early 90s late night variety show The Word. The magazine format of the series allowed for interviews, live music, features and even game shows. The flexible late-night format meant that guests could do just about anything to be controversial. Talking about his TV career to Jo Brown of Cheers Magazine, Lamarr said The Word was:

After leaving The Word, Lamarr was an outside presenter on The Big Breakfast from 1992 to 1996. Between 1995 and 1997 he appeared as a team captain in the surreal panel show Shooting Stars, where he displayed a mixture of dour boredom and contempt towards hosts Vic Reeves and Bob Mortimer who, in turn, mocked his "50s throw-back" appearance. Lamarr declined to return for the fourth series in 2002, claiming he did not want to be typecast for appearing on panel shows.[citation needed] He said of his experience on the show:

Lamarr was host of Never Mind the Buzzcocks when the show launched in 1996 and continued in this role for 17 series until 2005, when he announced that he was to take a break from the show. Although announced as a break, Lamarr didn't return to host the show; being replaced by Simon Amstell for the 19th series.

The two series of the sitcom Fifteen Storeys High were co-written by Lamarr with comedian Sean Lock and Martin Trenaman - although Lamarr was credited under his real name, Mark Jones.

Lamarr has previously presented shows on BBC GLR, BBC Radio Five Live and BBC Radio 1.

On 20 July 1998, Lamarr launched a new show on BBC Radio 2 called Shake, Rattle and Roll, where he plays tracks from his own sizeable record collection of obscure rock and roll gems. He also presents The Reggae Show series and Mark Lamarr's Alternative 60s, where he presents lesser known tracks from the 1960s.

On 22 April 2006, Lamarr started a new Radio 2 show called God's Jukebox. The show airs from Midnight to 3am on Saturdays where he plays a wide variety of music from the past 70 years including Soul, Ska, Reggae, Country, Gospel and Rap. He also, with Jo Brand, regularly covered the Jonathan Ross Saturday morning show on Radio 2 when Ross was away.

Mark presents a music show for British Airways on-board listeners as part of their in-flight entertainment. In this show he keeps up the eclectic nature of his radio shows by presenting a usually obscure mix of rock and roll, blues, reggae, soul and R 'n B.

Richard Allinson • Michael Ball • Zoë Ball • Ken Bruce • Alan Carr • Chris Evans • Bob Harris • Sarah Kennedy • Steve Lamacq • Mark Lamarr • Alex Lester • Janice Long • Stuart Maconie • Simon Mayo • Paul O'Grady • Dermot O'Leary • Lynn Parsons • Mark Radcliffe • Jeremy Vine • Johnnie Walker • Dale Winton • Terry Wogan • Steve Wright