George was born on the 15th of June, 1877, in Ogden, Kansas, where he grew up with seven siblings: three brothers and four sisters. He was commissioned as a Captain in the US Army in August of 1917 and he was deployed to Europe with the 132nd Infantry Regiment, 33rd Infantry Division. It was his actions on the 26th of September, 1918, in France that would earn him the Medal of Honor. The citation reads:

Becoming separated from the balance of his company because of fog, Capt. Mallon, with nine soldiers, pushed forward and attacked nine active and hostile machine guns, capturing all of them without the loss of a man. Continuing on through the woods, he led his men in attacking a battery of four 155-millimeter howitzers, which were in action, rushing the position and capturing the battery and its crews. In this encounter Capt. Mallon personally attacked one of the enemy with his fists. Later, when the party came upon two more machine guns, this officer sent men to the flanks while he rushed forward directly in the face of the fire and silenced the guns, being the first one of the party to reach the nest. The exceptional gallantry and determination displayed by Capt. Mallon resulted in the capture of 100 prisoners, 11 machine guns, four 155-millimeter howitzers, and one antiaircraft gun.

George received the Medal of Honor on the 9th of February, 1919, in a ceremony at Chaumont, France from General Pershing. He was married to Effie and they had two sons, Robert, who went on to serve as a paratrooper in World War 2, and George. George Henry Mallon died on the 2nd of August, 1934 at the age of 57 and he is buried in the Fort Snelling National Cemetery in Minneapolis, Minnesota: Section DS, Site 1-S.