Twenty-four buildings at Stow Maries Aerodrome, near Maldon, have been Grade II star-listed by the Department for Culture, Media and Sport.
The airfield site, which was used as a base for the 37th Squadron, Royal Flying Corps, is one of the few remaining of its kind in the country.
It was listed for its "rarity" and "historical importance", Heritage Minister John Penrose said.
The aerodrome was created in 1914 by the forerunner to the Royal Air Force.
It was one of several in the south east of England used to defend London from German Zeppelin airship and bomber raids during the conflict.
It ceased being used by the military in 1919 and was returned to agricultural use.
Its buildings remained and, according to English Heritage, is now "the largest known surviving group of Royal Flying Corps buildings on a WWI aerodrome".
In recent years the aerodrome was bought by private owners, who have had the buildings restored, and created a museum to tell its role during the war.
In 2010, a war memorial commemorating the 10 pilots of 37 Squadron killed in action during WWI was erected on the former parade ground.
Among the 24 surviving buildings are the officers' mess, accommodation huts, ammunition store, workshops, blacksmiths and mortuary.
On granting the listed status, Mr Penrose said the aerodrome was a "poignant reminder of the conditions in which they were working".
"I am listing Stow Maries for its rarity, its architectural interest, its value as a group and also of course for its historical importance as the first line of defence against German air raids," he said.
English Heritage chief executive Simon Thurley said: "The importance of Stow Maries is amplified by the approaching 100th anniversary of the Great War.
"It's in a remarkable state of preservation, full of historic interest and of great educational potential."
A World War I airbase in Essex has been granted listed status.