The 3rd Army () was a field army-level command within the ground forces of Austria-Hungary during World War I. It was primarily active on the Eastern Front against the Russian Empire and in the Balkans against Serbia and Montenegro. Later on, the 3rd Army took part in some fighting on the Italian Front before returning to the eastern theater by 1917 to repulse the Kerensky Offensive. Its remaining units were merged with the 7th Army in January 1918.