When he was three, Mayall and his parents - both of whom taught drama - moved to Droitwich Spa, Worcestershire, where he spent the rest of his childhood and performed in his parents' plays. He studied drama at the University of Manchester and gained fame by appearing at The Comedy Store with Edmondson, debuting there in 1980. They starred as "The Dangerous Brothers", supposedly a couple of naive but anarchic daredevils, and would perform comedy stunts on stage, often involving the likes of setting each other on fire. They effectively brought slapstick to the alternative comedy scene, albeit in a typically extreme fashion.

Mayall first broke into television with the character Kevin Turvey on the series A Kick Up the Eighties, which was first broadcast in 1981. A role as sociology student and Cliff Richard devotee Rick in The Young Ones sitcom in 1982 ensured wide public acclaim. The series was written by Mayall with long-standing friend Ben Elton and then-girlfriend Lise Mayer. Additional material was provided by comedian and actor Alexei Sayle. With many of his alternative contemporaries, Mayall went on to star in a number of the Comic Strip films.

Mayall subsequently starred in Filthy Rich & Catflap (1986) with Edmondson and Nigel Planer; and Bottom (1991-92, 1995), again with Adrian Edmondson (in which the two of them played similar roles to those they played in The Young Ones). His first notable solo work was as Conservative MP Alan Beresford B'Stard in the sitcom The New Statesman (1987-92) for Yorkshire Television, thereby also giving him a presence on ITV. He reprised the role in 2006 for the stage but this time as a Labour MP.

In 1986, Mayall achieved a number one hit in the UK singles charts when he and his co-stars from The Young Ones teamed up with Cliff Richard to record a new (and somewhat offbeat) version of Living Doll for the inaugural Comic Relief campaign. Mayall played Rick one last time in the subsequent stage show and has been a supporter of the Comic Relief cause ever since.

He has also appeared in films, notably Carry On Columbus and Drop Dead Fred; and six individual comedy dramas under the umbrella title Rik Mayall Presents in 1993. He also appeared in Blackadder series 1 as Mad Gerald, series 2 and 4 as Lord Flashheart, and on the millennium special episode Blackadder: Back & Forth as Robin Hood.

Mayall took his turn among many hundreds of other celebrities to read a story on the children's series Jackanory, relating extracts of Roald Dahl's George's Marvellous Medicine. Mayall lived up to his own slapstick past by pouring the medicine's ingredients over himself while telling the tale. He also made a little known film appearance in An American Werewolf in London as the second chess player alongside Brian Glover.

In 1998 he was seriously injured when he crashed a quad bike near his home in Devon, although he later made a full recovery. Both he and Edmondson have subsequently joked about this event in the various stage versions of Bottom, and the pair wrote the first draft of their Bottom feature film Guest House Paradiso while Mayall was in hospital.

Mayall has also played the role of Professor Adonis Cnut in the sitcom Believe Nothing and was Peeves the poltergeist in the first Harry Potter movie (Harry Potter and the Philosopher's Stone) but was cut out of the final edit.

In 2000, he appeared in the video production of Jesus Christ Superstar as King Herod. He joked in the Making Of documentary which was included on the DVD release that "the reason why a million, billion people want to come and see this is because I'm in it! Me and Jesus!"

Provided the voice of Cufflingk, one of the German falcons in the 2005 computer-animated film Valiant, and also is the voice of Edwin the Eagle in ShoeBox Zoo.

In a 2005 poll to find The Comedian's Comedian, he was voted amongst the top 50 comedy acts ever by fellow comedians and comedy insiders.

Mayall released an 'in-character' semi-fictionalised autobiography in September 2005 entitled Bigger than Hitler, Better than Christ (ISBN 0007207271). At the same time he was starring in a new series for ITV entitled All About George.

He is married and has two daughters and a son.