[1][2] Mylong was born Adolf Heinrich Münz, to Jewish parents in Velyki Mosty, Lviv Oblast, Ukraine, then governed as part of the Austro-Hungarian Empire.

He appeared in many Austrian and German silent films under the name Jack Mylong-Münz.

In 1934, following the annexation of Austria by Nazi Germany, Mylong emigrated to the United States.

There, he resumed his acting career, appearing in some 171 film and television roles between then and 1967.

He returned to Germany once, in 1951, to appear in the Curt Goetz comedy The House in Montevideo.