Osten went from the stage to film with two films made for television; Moa, Östen och Stella [Moa Östen and Stella] (screenplay;1974) and Barn i Afrika [Children in Africa] (director; 1978), before she debuted with the full-length feature film Mamma (1982). Like her stage productions, her films also deal with political issues, for instance "Skyddsängeln" ("The Guardian Angel") (1990) which focuses on political terrorism, although based on riots and demands for democracy in early 20th century Sweden. "Tala! Det är så mörkt", ("Speak up! It’s so dark") is about the wave of neo-Nazism that swept through Sweden in the 1980s and 90s and its link to unemployment among Swedish young people. For "Bröderna Mozart" ("The Mozart brothers") (1986), Osten was awarded a Guldbagge in 1987 for Best Director. Outside of Sweden, "The Guardian Angel", was selected for Un Certain Regard at the Cannes Film Festival in 1990.