The third of six sons of George Harrison; was for more than fifty years a prominent man in Chester as Surgeon to the Infirmary, then Consulting Surgeon, also three times Mayor. His eldest brother, George, practised as a partner with his father until his death about 1850. Another brother, Job, MRCS, was in active practice in Chester at the time of John's death. John Harrison studied at St Thomas's Hospital supplemented by instruction at the Aldersgate School, and began to practise at Knutsford; later he returned to his native Chester, where he was Surgeon and then Consulting Surgeon to the Infirmary, as well as Surgeon to the Lying-in Charity. In 1866 he was Secretary at the second meeting of the British Medical Association in Chester, and a representative of the Chester Branch. He began to fail in health more than eleven years before his death, which occurred at 18 Nicholas Street, Chester, on June 3rd, 1880.