Born in New Jersey, USA, into a Jewish family, Sadowitz was brought up in Glasgow. Following the breakdown of his parent's marriage, his mother returned to her native Scotland. A sickly child, Sadowitz took an interest in magic while still at school. He is today widely acclaimed as one of the best close-up magicians in the business. An accomplished practitioner of sleight of hand, he has written several books on magic and invented many conjuring innovations.

His comedy act is based around extreme offensiveness, breaking all taboos, using obscene language, and insulting the audience as much as possible. He famously opened the Montreal Comedy Festival with the line:

"Hello, moose-fuckers" and followed this up with:

"I tell you why I hate Canada, half of you speak French, and the other half let them" He was promptly knocked unconscious by an outraged audience member.

His refusal to moderate his comedy act has led to difficulties in his career: his debut BBC television show The Pall Bearer's Revue attracted a record number of complaints and was promptly moved to a graveyard slot and has never been repeated. And outbursts of his savage comedy routines during his conjuring shows have sometimes alienated him from the more conservative magic community. In his early days he was managed by anarchic comedian and club proprietor Malcolm Hardee, whose provocative selling line was that Sadowitz was too shocking to appear on TV; this may have actively put off TV producers from booking him.

Some of his earliest performances as a magician, with comic asides, were at a Glasgow pub (the Weavers Inn) run by future comedienne Janey Godley. He first came to prominence as a comedian in the 1980s, reacting against the politically correct Alternative Comedy movement. An early influence was the 'Derek & Clive' sketches by Peter Cook and Dudley Moore, which much of his comedy emulates in its provocativeness and sheer offensiveness (he once described the Derek & Clive monologues as "comic poetry"). As a bet with fellow comic Nick Revell, he produced one of his most famous lines of that era:

"Nelson Mandela, what a cunt. Terry Waite, fucking bastard. I dunno, you lend some people a fiver, you never see them again". His hit 1987 Edinburgh Fringe show Total Abuse was later turned into the album Gobshite, but was soon withdrawn due to fears it may have libelled Jimmy Savile. After a brief run as a columnist for Time Out magazine, he returned to Edinburgh in 1989 with Lose Your Comic Virginity, continuing to shock with attacks on sacred cows like Lenny Henry and the Lockerbie air crash. In the 1990s, he was part of a short-lived double act with Logan Murray, in the show Bib & Bob.

In 1999 he performed for a month at the Penny Theatre in Camden, London, performing close-up magic to 30 people at a time and the following year he performed a stand-up show in Covent Garden with Logan Murray titled Late Night Filth. The show was nearly two hours of sketches aimed at alienating almost everyone, including stamping on a blow-up doll of the recently deceased Linda McCartney, and tipping Logan Murray, dressed as Superman, out of a wheelchair into the audience (a reference to the paralysis of Christopher Reeve). At one point he spat in the face of a drunken heckler who was constantly interrupting the show. His final act was to strip naked and run for a few minutes from side to side, prompting a mixture of disgust and hilarity from the audience.

He performed two separate shows at the 2005 Edinburgh Fringe, a stand up comedy show (Not For The Easily Offended) at The Queens Hall and Jerry Sadowitz - Card Tricks & Close Up Magic at The Assembly Rooms. The comedy show included a character named "Rabbi Burns", a cross between a Jew and the famous Scottish poet, and contained many shocking jokes, for instance: