Bennett was born November 17, 1841 in Union City, Michigan. The Bennett family left Michigan when Orson was young and settled in Dubuque, Iowa. There he attended school and became certified as a teacher.
After the Civil War, Bennett married and moved to Le Mars, Iowa where he operated a hardware store. In about 1880 the Bennetts moved to Bismarck and then Fargo, Dakota Territory, where he worked in the grain and real estate business.
In later years he moved to Washington, DC and finally to Philadelphia, Pennsylvania to continue his career in real estate.
He died January 8, 1904 and is buried in Westminster Cemetery, Bala Cynwyd, Pennsylvania.