Daniell played high school football for Mt. Lebanon High School and The Kiski School in Pennsylvania. After graduating, he attended Ohio State University and played college football for the Ohio State Buckyes between 1938 and 1941. He was selected in the 12th round of the 1942 NFL Draft by the Chicago Bears, but delayed a professional career to work for his family's steel business and serve in the U.S. Navy during World War II. Daniell was deployed in the Pacific theater and fought in the Battle of Okinawa. He rose to the rank of lieutenant and was awarded numerous service stars for his role in combat.