Mason gained infamy by allegedly giving Ed Sullivan the finger on a live telecast of Sullivan's weekly variety show in 1962. He denied that he made an obscene gesture, insisting that he flashed numerous fingers and that Ed Sullivan assumed he gave him the finger. He later retaliated against Sullivan with a libel suit in the New York State Supreme Court and won. It would be a year and a half before Sullivan would finally let him back on his show.

Surviving videotape showed Mason talking through his bit, and then looking to his right, or viewers' left, toward Sullivan and commenting on the fact that Sullivan was giving him finger-signals, and expressed bewilderment over why Sullivan was signalling him. Presumably Sullivan was trying to tell Mason to wrap up his segment. Mason continued commenting, talking toward Sullivan instead of the audience, and at the same time swung his right hand around, apparently mocking Sullivan's signalling, and with the middle finger slightly separated from the others, leaving Sullivan with the impression (correctly or otherwise) that Mason had given him "the finger" on live TV. The camera then cut to Sullivan, who was clearly agitated over what had just transpired; his arms were folded tightly and he was staring downward, presumably holding his sense of outrage inside as best he could, at the perceived obscene gesture, and perhaps also at Mason's general truculence.

In 1991, Mason was criticized by African-American organizations such as the NAACP when he called New York mayor David Dinkins "a fancy schvartze with a moustache." He later apologized.

Mason also cofounded the organisation One Jerusalem to defend against the Oslo peace agreement. It has as cause to "saving a united Jerusalem as the undivided capital of Israel."

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.

Mason had several one-man comedy stage shows over the years. One was called The World According to Me, which was well-received. Later he had a show called Politically Incorrect, which ran into copyright problems as it was around the time that Bill Maher's TV show of the same name was on the air. Mason eventually added his name to his show's title to settle the situation.

In November of 2005 Mason started a daily talk show, "The Jackie Mason Show". The show can be seen nightly on the CN8 network on Comcast cable television.