After completing the ROTC program and graduating from the University of Kansas Mitchell worked at Eastman Kodak for a few months before serving two years with the U.S. Army Corps of Engineers. He received the U.S. Army Commendation Medal for Outstanding Military Service and achieved the rank of 1st Lieutenant. Mitchell then held leadership positions at major corporations in the Fort Smith, Ark., region. In 1970, he was offered a position as engineering manager at Tetra Plastics near St. Louis. By 1972 he had been promoted to vice president. In 1980, Tetra began working with the sporting equipment giant Nike to develop uniquely engineered cushioning systems for the Nike Air line of shoes. In 1988, Mitchell was promoted to president and COO of Tetra and assumed general management responsibilities. In 1991, Mitchell negotiated the sale of Tetra Plastics to Nike and was named the president and CEO of the new Nike IHM subsidiary. In 1993, the plant was flooded with 7-feet of water when the Missouri River breached its levees. The plant employed about 250 people and was Nike's only Air technology materials and components manufacturing plant. Mitchell quickly moved the operation to a nearby dry location. Twenty-seven days after the flooding, damaged equipment had been rebuilt, workers were back on the line and Nike IHM averted an international shortage of soles. In January 2000, Mitchell was named vice president for advanced research and development for Nike Global Footwear.
Mitchell holds 11 patents. He has been very active in the Society of Plastic Industry Sheet Products — serving as its president for two years— as well as serving on the National Board of Directors of the Society of Plastic Industry.