Mitchell enrolled in beauty school at age sixteen, and after completing his five year apprenticeship began working at various hair salons, following in his mother's footsteps. He won multiple hairstyling competitions and then joined Vidal Sassoon in the 1960s, becoming one of the best known stylists in London. He left Sassoon in 1966 and went on to open several salons in the United States.
In 1980, he founded John Paul Mitchell Systems with his business partner John Paul DeJoria. The goal of the company was to market professional hair care products through salons. Its first product was Hair Sculpting Lotion.
Mitchell died of pancreatic cancer in April 21, 1989.