Having obtained his Matura degree, he served in a mountain artillery regiment of the Austro-Hungarian Army in World War I, discharged in 1918 with the rank of an Oberleutnant.

After the war, Hörbiger took drama lessons and began his acting career in 1919 at the city theatre of Reichenberg (Liberec).

His fame grew when in 1926 he was employed by director Max Reinhardt at the ensemble of the Deutsches Theater in Berlin, reaching a high point with his appointment at the Vienna Burgtheater in 1940.

After the war, he resumed his career playing the porter who "talks too much" in Carol Reed's British film classic The Third Man (1949).

In his later years he again concentrated on theatre acting at the Burgtheater, where he last premiered in 1979 with Elias Canetti's Komödie der Eitelkeit ("Comedy of vanity").