Kelly began his career working on a short project for the Michigan Geological Survey with K. Spiroff, and when the project was completed moved on to become a mining engineer with the Tennessee Coal, Iron and Railroad Company in Birmingham, Alabama. After the heat forced him north again, he joined North Range Mining Company where he rose rapidly through the ranks to Assistant to the Manager. From 1947 to 1963, he was engaged by Cleveland-Cliffs as Assistant to the Chief Engineer and later as Chief Engineer. He was also actively involved in the opening of the Ohio, Humboldt, Republic and Empire Mines. His leadership as General Manager from 1963 to 1983 of the newly-formed Eveleth Taconite Company helped contribute to its growth of a six million ton per year operation. Kelly retired in 1983. Kelly served as Chair of both the Upper Peninsula and Minnesota Sections of the American Institute of Mining, Metallurgical, and Petroleum Engineers - Society of Mining Engineers. He is the Director of the United States Hockey Hall of Fame in Eveleth, Minnesota. He is a member of the Duluth Scottish Heritage Association and an active member in his church. Kelly was honored with the MTU Board of Control Silver Medal in 1982 and was inducted into the Michigan Tech Academy of Mining Engineers in 1995.

Kelly received a BS in Geology and a BS in Mining Engineering from Michigan Technological University in 1939 with honor.