The 31st Air Defense Artillery Brigade is an air defense artillery brigade of the United States Army based at Fort Sill, Oklahoma.

The 31st Air Defense Artillery Brigade was constituted on 1 January 1918, during World War I, in the National Army as Headquarters, 31st Heavy Artillery Brigade, Coast Artillery Corps at Key West, Fla. but would see numerous name changes over the lifetime of the unit. The unit, commanded by Brigadier General George Washington Gatchell, rapidly transitioned into World War I where the brigade earned four battle streamers for participation in the campaigns Aisne-Marne, Oise-Aisne, Meuse-Argonne, and Champagne 1918.

The unit was demobilized at Fort Lewis, Wash. 30 June 1921. The brigade was reconstituted 14 October 1936 in the regular Army as Headquarters, 31st Coast Artillery Brigade and was later designated as Headquarters and Headquarters Battery, 31st Coast Artillery Brigade. In November 1942 the brigade was activated as Headquarters and Headquarters Battery, 31st Anti-Aircraft Artillery Brigade as part of the coastal air defense stationed at Camp Haan, Cali. and was later deployed to the European Theater where it participated in and earned three more battle streamers for campaigns in Rome-Arno, Southern France, and the Rhineland. On 30 June 1946, the brigade was deactivated at Laned-Sebold, Germany. This unit would encounter numerous activations and inactivations over the years to come to include a 1946 inactivation in Germany, reactivation in 1948 at Fort Bliss, Tex. and in 1958 was reorganized as Headquarters and Headquarters Battery, 31st Artillery Brigade.