Like his father, John Sherwin (1901–1991) started out in the banking business. After graduating from Yale (B.S., 1923), the native Clevelander joined the Union Trust Company and was elected vice president in 1927. The following year, he left to become president of Midland Bank; when Cleveland Trust absorbed Midland, he was appointed executive vice president. In 1941, Sherwin left banking to become a partner of the iron-ore producer Pickands Mather; in 1960, he was named president of that company (later becoming chairman of the board) and its affiliated Interlake Steamship Company. He served on the boards of numerous commercial and industrial concerns and was a director of the American Iron and Steel Institute and the Lake Carriers Association.

During his rise at Pickands Mather, John Sherwin had found time to be a member of the board of organizations as diverse as the Horace Kelly Art Foundation, Cleveland Museum of Natural History, Cleveland Chamber of Commerce and Cleveland Clinic Foundation (he would ultimately serve as a trustee of the internationally known medical center for a record 57 years). He was preceded on the Cleveland Foundation board by his first cousin once removed, Belle Sherwin, a member of the first distribution committee (1917–24). In 1973, he and his wife, Frances Wick Sherwick, established the Sherwick Fund. Their son, John Jr., was appointed to the Cleveland Foundation’s distribution committee in 1996 and later served as its chairman.