John O’Donnell grew up in Chicago and received his early education at Park Side School, Saint Thomas School, Saint Ignatius High School, and De Paul College. He then attended Saint Viator’s College in Bourbonnais, Illinois, and then Niagara University in Niagara Falls, New York. He received theological training at Saint Viator’s Seminary in Bourbonnais, and was ordained a Vincentian Catholic priest on May 13, 1911. He was commissioned in the Veteran Corps, 2d Illinois Infantry in 1916, and served on the Mexican border that year. He was commissioned a chaplain in the Regular Army on August 5, 1917. He served in Chicago, and then at Camp Logan in Texas, before going to France with the American Expeditionary Forces in World War I. He was wounded in France from a gas attack, and received the Distinguished Service Medal and Silver Star, and was discharged from active duty on May 1919 as a captain, later retiring from reserve service as a major. In 1929 he was Pastor of Saint Ethelreda Church when he contracted pneumonia. Slow to recover, he travelled to Atlantic City for rest, and to convalescence, and died on May 11, 1929.