The Austrian resistance (German: Österreichischer Widerstand) was launched in response to the rise of fascism across Europe and, more specifically, to the Anschluss in 1938 and resulting annexation of the Austrian Republic by Nazi Germany.

An estimated 100,000 people were reported to have participated in this resistance with thousands subsequently imprisoned or executed for their anti-Nazi activities.

One cipher of the Austrian resistance used from 1944 onward was O5, indicating "OE," another way of writing the letter Ö which begins the German name of the country; '5' indicated the fifth letter of the alphabet (E). This sign may be seen at St. Stephen's Cathedral, Vienna. From 1939, the Nazi regime did not use the term Österreich; when Austria was referred to, it was as Ostmark ('Eastern march'), with the implication that Austria was merely an outer region of Greater Germany and not a country in its own right.

The Moscow Declarations of 1943 laid a framework for the establishment of a free Austria after the victory over Nazi Germany. It stated that "Austria is reminded, however that she has a responsibility, which she cannot evade, for participation in the war on the side of Hitlerite Germany, and that in the final settlement account will inevitably be taken of her own contribution to her liberation."

The Austrian resistance groups were often ideologically separated and reflected the spectrum of political parties before the war.

Austrian resistance efforts included a group led by priest Heinrich Maier. This resistance group sought to reestablish a Habsburg monarchy after the war. It played a large role in providing the Allies with information on the production sites of the V-1, V-2 rockets, Tiger tanks, and aircraft such as the Messerschmitt Bf 109 and Messerschmitt Me 163 Komet. The intelligence they provided, later uncovered by the Gestapo, was necessary in enabling the Allies to conduct precise airstrikes, minimizing civilian casualties. The group maintained contact with Allen Dulles, head of the U.S. OSS in Switzerland, and their information contributed to key operations such as Operation Crossbow and Operation Hydra, both of which were precursors to Operation Overlord. The Maier group was also one of the earliest to report the mass murder of Jews, utilizing contacts at the Semperit factory near Auschwitz.

In addition to armed resistance, numerous individuals provided support to Jewish families during the Holocaust. These efforts included hiding individuals, managing or exchanging their property to generate funds, and aiding their escape from Nazi persecution. These actions carried immense personal risk, as assisting Jews was punishable by imprisonment or death in Nazi concentration camps. Among these individuals were Rosa Stallbaumer and her husband, Anton. Arrested by the Gestapo in 1942, they were sent to Dachau concentration camp. Although Anton survived, Rosa Stallbaumer did not; transferred to Auschwitz, she died there at age 44.

The other groups often referred to partisans in the Salzkammergut (group "Willy Fred") or in the Ötztal. The resistance group in Ötztal founded by Wolfgang Pfaundler [de] and Hubert Sauerwein in 1941. Around 50 people belonged to this group. Apart from their political activity, in the beginning they did not go beyond the construction and arming phase.