Amann was born in Munich on November 24, 1891; during World War I he was Adolf Hitler's Sergeant. Amann lost an arm in a grenade attack. He joined the NSDAP in October 1921 and became its chairman in 1922 and president of the Reichspressekammer (Reich Media Chamber) in 1933. He also led the publishing company Eher-Verlag, which, among other things, published the SS magazine Das Schwarze Korps. Perhaps Amann's most notable contribution to history was persuading Hitler to retitle his first book from Four and a Half Years (of Struggle) Against Lies, Stupidity and Cowardice to Mein Kampf, which he also published, and became a major source of Eher-Verlag's income.
During the Third Reich, he became (by forced appropriation) the largest newspaper publisher in Germany and made enormous profits off Nazism. In this role, he established Nazi control over the industry and gradually closed down those newspapers that did not fully support Hitler's regime.
However, as a party official, Amann lacked talent, being a poor speaker and debater. In addition, his handwriting was illegible, thus his deputy, Rolf Rienhardt, performed these duties for him.
Arrested by Allied troops after the war, Amann was found guilty of being a Hauptschuldiger (Prominent Guilty Party) and sentenced to ten years in a labour camp on September 8, 1948, but was released in 1953. He also lost his property and pension rights and died in poverty on March 30, 1957, in Munich.