Zagórski began his military service in 1900 in the Austro-Hungarian Army. On August 18, 1902, he was promoted to Second Lieutenant of Artillery. In 1910, he graduated from the General Staff Academy in Vienna and was promoted to Chief of Staff of the 8th Infantry Brigade of the Austro-Hungarian Army in Cracow. In 1911, he was transferred to the (Evidenzbureau) of the Austro-Hungarian Army, where he was responsible for leading irregular warfare in the Vistula Land, aimed at destabilizing said region of the Russian Empire. Zagórski was appointed as an official in the Second Branch of the General Staff in Vienna, where he commanded the so-called "Hauptkundschaftstellen" in Cracow, Przemyśl, and Lwów.