Beginning as an iron moulder, Parker developed and patented a number of mechanical and industrial inventions, including the John P. Parker tobacco press and harrow (or pulverizer), patented in 1884 and 1885. He had invented the pulverizer while still a young man in Mobile in the 1840s. Parker was one of the few blacks to patent an invention before 1900. In 1865 with a partner, he bought a foundry company, which they called the Ripley Foundry and Machine Company. Parker managed the company, which manufactured engines, Dorsey's patent reaper and mower, and sugar mill. In 1876 he brought in a partner to manufacture threshers, and the company became Belchamber and Parker. Although they dissolved the partnership two years later, Parker continued to grow his business, adding a blacksmith shop and machine shop. In 1890, after a destructive fire at his first facility, Parker built the Phoenix Foundry. It was the largest between Cincinnati and Portsmouth, Ohio.