Adolphe Guillaumat was born in Bourgneuf, Charente-Maritime. He graduated first from his class of 1884 at the Saint-Cyr military academy.
His early career was partly spent in the French Colonies (Algeria, Tunisia, Tonkin, China). He was appointed a sub-lieutenant of infantry in October 1884. Four years later he was promoted lieutenant. In November 1893 he became a captain and was transferred to the 147th infantry regiment. In 1903 he was appointed professor of military history at St. Cyr, and later became lecturer on infantry tactics at the École de Guerre. He was promoted lieutenant-colonel in 1907 and colonel in 1910. In January 1913, he was appointed Director of Infantry, and obtained the rank of Brigadier General in October of that year.
At the start of World War I, he was chief of Minister of War Adolphe Messimy's military cabinet. When the latter left office, Guillaumat was appointed as the head of the 33rd Infantry Division on August 30, 1914, and then of the 4th Infantry Division on December 9, 1914. He led the 1st Army Corps from February 25, 1915, and on December 15, 1916, he replaced Robert Nivelle as commander of the Second Army, when the latter was made commander-in-chief of the French Army.
Guillaumat was sent to replace General Sarrail as commander of the Allied Army of the Orient in Salonika in December, 1917. He laid the plans later executed by his replacement, General Franchet d’Esperey, and rebuilt the relations with France's allies somewhat damaged by his predecessor. Guillaumat was recalled to Paris on 17 June 1918 and replaced with Franchet d’Esperey.
There, he replaced Auguste Dubail as Military Governor of Paris. After the success of the Second Battle of the Marne, he was appointed to the Supreme War Council. He then returned to active command as commander of the Fifth Army, which he led through the Ardennes at the end of the war.
Following the Armistice, Guillaumat was appointed Commander in chief of Allied occupation forces in the Rhineland. He was criticised for his failure to take suitable precaution against cold weather in the winter of 1928/9 which led to some of the soldiers under his command freezing to death.
He was a Minister of War in a short-lived (June 23 – July 19, 1926) government led by Aristide Briand, who had been one year his senior at the Nantes Lycée.
Adolphe Guillaumat married Louise Bibent from Toulouse on July 17, 1906, and had two sons: Louis, who became an Ophthalmologist, and Pierre, who became a Civil servant and served as a Minister of the Armies of General De Gaulle after the latter's return to power from June 1, 1958, to February 5, 1960.
General Guillaumat was a practising Catholic and an admirer of Frédéric Bastiat.