Streicher served in the German army during World War I and afterward taught elementary school in Nürnberg. He joined the Nazi Party in 1921, becoming one of the earliest Nazis in southern Germany and a close friend of Adolf Hitler (Hitler, Adolf). In 1925 Streicher was appointed gauleiter (district leader) of Franconia, which, after the Nazis came to power in 1933, he administered from his chief bailiwick, Nürnberg. As the founder (1923) and editor of the anti-Semitic weekly newspaper Der Sturmer, Streicher achieved a position of great wealth and influence in Nazi Germany. Der Sturmer's crude anti-Jewish invective provided a focus for Hitler's persecutory racial policies; the newspaper initiated the general campaign that led to the passage of the Nürnberg Laws in 1935.

Streicher's irresponsible behaviour and sexual and sadistic excesses eventually alienated many of his fellow party officials, and he was stripped of his party posts in 1940 after a commission investigated the scandalous irregularities of his business transactions and personal life. He continued to serve as editor of Der Sturmer throughout the war years, however, owing to Hitler's protection of him.