Born in 1934 in Riverton, New Zealand, Arnett later naturalised as an American citizen and had lived in southern California since 2014.
Edith Lederer, a former colleague who still works at AP, told the agency: “Peter Arnett was one of the greatest war correspondents of his generation – intrepid, fearless, and a beautiful writer and storyteller.
“His reporting in print and on camera will remain a legacy for aspiring journalists and historians for generations to come.”
Meanwhile, Nick Ut, a retired photographer who worked with Arnett in Vietnam, said he was “like a brother”.
“His death will leave a big hole in my life,” he told AP.
Arnett is survived by his wife Nina Nguyen and their children, Andrew and Elsa.