George Franklin Cullinan was born on October 27, 1879 at Elk Point, Dakota Territory. He was the son of Joseph Francis Cullinan (1846-1890) and Catherine Agnes Terese Pellerin (1854-1903).
Cullinan served in the Army during the Spanish-American War in 1898. In 1917, he enlisted for service in the First World War. He was responsible for the establishment of the Post Office in Arthur, Nebraska.
On February 21, 1919, he married Margaret Caroline Leonard (1891-1975) in Shelby County, Tennessee. They had three children, Mary Elizabeth (Betty) Cullinan, Mark Joseph Cullinan and Georgia Ann Cullinan.