The novelist died Monday, agent Margaret Connolly said.
Koch wrote eight novels over the course of his 55-year writing career, most notably "The Year of Living Dangerously," which was adapted to the silver screen in 1983 by director Peter Weir and earned a best supporting actress Oscar for Linda Hunt.
Koch's other novels include 1995's "Highways to War" and "Lost Voices," which was published last year, the Los Angeles Times said Thursday.
His novels often explored his home country's engagement with its Asian neighbors, something that could be attributed to his desire to leave his native Tasmania, the newspaper said.
"Koch has an extraordinary power of evoking place," novelist and critic Graham Greene once wrote, "and I feel now that Tasmania is part of my memory."
Koch is survived by his second wife, his son from his first marriage, grandchildren, a brother and sister.