Miller, who was 89, retired in 1983 after a 45-year career that took him to battlefields from World War II to Vietnam.
He was with the U.S. Marines when they landed at Guadalcanal, covered Gen. George Patton in Europe and was captured and held briefly by North Vietnamese soldiers in Cambodia.
Miller's sister in California told the Honolulu Advertiser her brother had suffered several strokes since December, was seriously ill the past six weeks and died Monday. She said there would be no funeral and that his ashes would be spread at sea off Hilo.
Miller often worked at UPI's Honolulu bureau, which he managed for several years. But he spent most of his career on assignments that took him around the world.
"My god, there wasn't a place he couldn't go without knowing everybody," Gordon Sakamoto, a UPI colleague, told the Advertiser. "Everything he did was at top speed. He was a great newsman."
UPI Senior Editor Bruce Cook of Bethel Park, Pa., worked with Miller in Honolulu and they stayed in touch over the years.
"Bob Miller was a hero to me and other young reporters in Hawaii in the '60s," Cook said. "Bob had assignments most reporters only dream about. He was a colorful writer and a great storyteller."