For most of his childhood, Dennis O'Rourke lived in a small country town, where his parents ran a failing business, until he was sent to a Catholic boarding school for his secondary education. In the late 1960s, after two years of fruitless university studies, he went travelling in outback Australia, the Pacific Islands and South East Asia. During this period he worked as a farm hand, salesman, cowboy, a roughneck on oil rigs, and as a maritime seaman. He also taught himself photography and dreamt of becoming a photojournalist. Wanting to make documentary films, he moved to Sydney where the Australian Broadcasting Corporation employed him as an assistant gardener. He later became a cinematographer for that organization.

From 1974 until 1979 he lived in Papua New Guinea, which was in the process of decolonisation. He worked for the newly independent government, teaching documentary filmmaking skills to Papua New Guineans. His first film, Yumi Yet - Independence for Papua New Guinea, was completed in 1976, and it was widely acclaimed.