In 1921, Twardowski portrayed Joshua Nesbitt, Lord Horatio Nelson's stepson, in the German silent Lady Hamilton.
In 1933; he played Von Bergen in the war drama Private Jones, a prince in Adorable and a lawyer in The Devil's in Love.
In 1935, Twardowski appeared as Count Nicholas of Hungary in the Cecil B. DeMille film The Crusades starring Loretta Young.
It would be two years before Twardowski appeared in another movie and that was a small part in the romance Thin Ice starring Sonja Henie and Tyrone Power.
Next Twardowski appeared in another spy thriller Espionage Agent starring Joel McCrea which was released just three weeks after Germany invaded Poland.
He next played an uncredited role as a sergeant in The Pied Piper starring Monty Woolley as an Englishman trying to get out of German-occupied France with a group of children.
In 1943, Twardowski appeared in Lang's Hangmen Also Die!, portraying the notorious Nazi SS Commandant Reinhard Heydrich.
Twardowski played a German officer in Raoul Walsh's Background to Danger starring George Raft, Sydney Greenstreet and Peter Lorre.
Later that year, he had a small part in the war drama The Cross of Lorraine starring Gene Kelly, Cedric Hardwicke and Lorre.
Twardowski's last two movies were 1944 war dramas; first he appeared as a doctor in The Hitler Gang and later as a German Red Cross representative in Resisting Enemy Interrogation.