He was born at Alcsút, Hungary. On 15 November 1893, in Munich, he married Princess Augusta Maria Louise of Bavaria (1875 – 1964), daughter of Prince Leopold of Bavaria (1846 – 1930) and his wife Archduchess Gisela of Austria (1856 – 1932).

Archduke Joseph August became thus from 1893 "grandson - in - law" to Emperor Francis Joseph. His wife's mother Archduchess Gisela was the eldest surviving daughter of Austrian Emperor Francis Joseph and Empress Elisabeth ("Sisi"). The young couple's children, starting from Archduke Joseph Francis of Austria (1895 – 1957), were born in their great - grandfather's lifetime. Other Children were: Gisela Auguste (1897 – 1901), Sophie Klementine (1899 – 1978), Ladislaus Luitpold (1901 – 1946), Matthias Joseph (1904 – 1905), Magdalena Maria (1909 – 2000).

Joseph August began his military career in 1890 when he was commissioned into Infantry Regiment #1 as a Leutnant. He was soon promoted to Oberleutnant and was transferred to Infantry Regiment #72 in 1893. He was transferred to Dragoon Regiment #6 in 1894 and then transferred to Honvéd Hussar Regiment #1 by the Kaiser and promoted to the rank of Major. He took command of this regiment in 1904 and then went on to command 79th Honvéd infantry brigade in 1908 then finally the 31st infantry division at Budapest in 1911.

August was highly decorated before World War I broke out. Some of his awards include The Bronze Military Merit Medal, Grand Cross of the Order of Saint Joseph, The Marianer Cross of the Deutscher Ritterorden, The Order of the Black Eagle, The 1st Class of the Order of the Red Eagle, The Grand Cross of the Victorian Order of Great Britain, the Grand Cross of the Order of Karl III, and the Grand Cross of the Bulgarian Order of Cyrill and Methodius.

In 1914 August was involved in combat in the Galician theatre and took command of the VII Corps and was involved in fighting in the Carpathian Mountains. After Italy became involved in the war he was transferred to the Carinthian border and involved in fighting the Isonzo army. August remained on this front until the 9th battle of the Isonzo in 1916 a period in which once again he was highly decorated. August was highly liked by his troops, especially those of Hungarian nationality.

In November 1916 August was put in command of the Heeres front fighting against Russian and Romanian forces. In January 1918 he was put in command of the 6th army in the Southern theatre and that July took over the Armeegruppe Tirol, which was the 10th and 11th Armies. Finally he was put in command of the Heeresgruppe Kövess in the Balkan theatre. He became the last field marshal (Generalfeldmarschall) of the Austro - Hungarian Army on October 24, 1918, as an attempt by Kaiser Karl to calm Hungarian nationalists.

On October 27, 1918 Emperor Karl made August the "Homo Regius" of Hungary, but August asked to be released from his oath of allegiance from the Kaiser. He then began negotiations and appointed Graf János Hadik to build a new national government. However the Aster Revolution broke out on October 31, 1918, deterring his plans. In November, the independent Hungarian Democratic Republic was proclaimed, only to be replaced a few months later by the communist Hungarian Soviet Republic. This revolution was to fail: the popular August survived unharmed and once again became the head of state "Reichsverweser" (regent) and appointed a Prime Minister. Since the Allied forces declined to accept Archduke Joseph as Hungary's head of state, he was forced to resign on 23 August 1919. In 1920 the archduke became the first knight of the Hungarian Order of Vitéz, in 1927 he became a member of the newly established House of Lords. He later became an honorary member of the Hungarian Academy of Sciences and was its president from 1936 - 1944. He fled Hungary for the United States in 1944 but later returned to Germany. He died in 1962 at Rain near Straubing.

His eldest son Archduke Joseph Francis of Austria had predeceased him, dying in 1957. Thus Joseph August's main heir was his eldest grandson Archduke Joseph Arpad of Austria (born 1933), the eldest son of Joseph Francis and his wife Princess Anna of Saxony. Joseph Arpad is married to Princess Maria of Löwenstein - Wertheim - Rosenberg, and had children in Joseph August's lifetime. His eldest son is Archduke Joseph Karl (born 1960). Joseph August's granddaughter Archduchess Ilona of Austria (b. 1927) married George Alexander, Duke of Mecklenburg. Her son George Borwin, Duke of Mecklenburg, is the current head of the House of Mecklenburg - Strelitz.