Mike Williams was born in Liverpool on 24 February 1940, the younger son of George H Williams and his wife, Margaret (née Watterson). His elder brother, Pete Williams, also became a cartoonist.
He was educated at Quarry Bank High School for Boys (where his contemporaries included John Lennon). Then, from 1957, he trained as a commercial artist and illustrator while working in the art studios of Henry Pybus and Littlewoods. 

In 1964, he married Joan Pimblott, and together they would have two daughters.
Becoming a freelance cartoonist in 1966, Williams sold his first cartoon to Punch in the following year, and has contributed regularly to that and many other periodicals. These include The London Magazine, The Oldie, Playboy, Private Eye, The Spectator and The Times. His cartoons for Punch have been collected in Oh No! Not the ’23 (1987) and You Can’t Still Be Hungry (1988), and he also collaborated with Albert Rusling on The Very, Very, Very Last Book Ever: Part One (1986).
During the 1990s, Williams deputised for Jak on the Mail on Sunday, and in 1997 he was briefly the Cartoon Editor of Punch. Throughout 2008, while Liverpool was the European City of Culture, he commented on its events in regular cartoons for the Liverpool Echo.
Williams has provided illustrations for print and television advertising, most notably drawing the ‘polar bear’ for the Swiss bank, Julius Bär, over a period of 15 years. He has also produced greetings cards for Valentines of Dundee and the Ink Group.
Mike Williams lives in Heswall, Wirral, Cheshire.
His work is represented in the collections of the British Museum.