Herbert Gordon Carter was born at Sydney, New South Wales, on 24 March 1885 to parents Herbert and Antoinette Carter. An electrical engineer by trade, he enlisted on 3 September 1914 at the age of 29. Enlisting with the 1st Infantry Battalion, Carter was appointed the rank of lieutenant. On 18 October 1914 he embarked from Sydney on HMAT Afric. His brother, Captain Robert Burnside Carter, also served during the First World War with the British Army.

Serving at Gallipoli in 1915, he was promoted to the rank of captain and then major that same year. In 1916 he was transferred to the 53rd Infantry Battalion and later the 5th Pioneer Battalion. In August 1916, he was promoted to the rank of lieutenant colonel and took over command of the 5th Pioneer Battalion for the remainder of the First World War.

On 31 January 1917, Carter married Lydia Kate King from Orange, New South Wales, who was then working with the 2nd Australian Auxiliary Hospital at Southall, England. Carter received a mentioned in despatches three times and he was awarded the Distinguished Service Order in January 1918. Herbert Carter returned to Australia on 5 April 1919.