In Winchell's earlier years, he worked as a hypnotist helping people undergo surgery. Winchell had also been an inventor, with some of his ideas being an artificial heart and a flameless cigar lighter. A patent for one of his ideas, a disposable razor, was disapproved on the basis it was considered ridiculous for people to buy razors to throw them away after a single use. Ironically, that concept would soon become hugely popular.
Paul Winchell got into show business as a ventriloquist and had his own show called The Paul Winchell Show. He operated multiple puppets, two of his best known were named Knucklehead Smiff and Jerry Mahoney. The Jerry Mahoney puppet now resides in the Smithsonian Institution in Washington, D.C..
During Winchell's time on Winnie the Pooh and Gummi Bears in the later part of the 1980s, he had taken an interest in famine and malnutrition. With actor Ed Asner, Winchell lobbied Congress to appropriate foreign aid for landlocked nations to encourage the breeding of the tilapia fish, which was a source of protein and could survive in different types of waters. Although well researched, their idea was ultimately disapproved as it was felt aquaculture in Third World nations that lacked access to the ocean was inadvisable.
Paul Winchell was married three times, fathering five children. Through his second marriage to British actress Nina Russel, he had a daughter, April Winchell, who later became a voice actress herself.