From 1903 Froelich was a colleague of Oskar Messter, one of the advance guard of German cinema, for whom initially he worked on the construction of cinematographic equipment.
As cameraman for Messter's weekly newsreels he filmed among many other things the aftermath of a train accident on the Berlin elevated railway on 28 September 1908, one of the worst transport disasters of the time.
In 1929 Froelich made the first German sound film, Die Nacht gehört uns ("The Night Belongs To Us").
In 1937 he was awarded a professorship and in 1939 was appointed president of the Reichsfilmkammer, an office which he retained until the end of the war in 1945.
The Reichsfilmkammer was subordinate to the Reichskulturkammer, which as a National Socialist trade organisation regulated and controlled access to all artistic professions.