Rooney died just five weeks after his 1,097th and final appearance on the news magazine show. He wrote his first opinion piece, "An Essay on Doors," in 1964, which long-time friend Harry Reasoner voiced, The Hollywood Reporter said.
While serving as an Army draftee in World War II, Rooney began writing for the "Stars and Stripes" military newspaper. By 1949, he was working for CBS in New York as a writer for "Arthur Godfrey's Talent Scouts" and later the "The Garry Moore Show" before moving to the news division, ABC News said.
The rumpled-looking Rooney, often described as looking like a gruff uncle – or grandfather in his later years – sat behind a cluttered desk he had built himself and most often spoke of simple and small things in life.
His old Underwood typewriter was usually in view, leading him once to observe: ""I had one typewriter for 50 years, but I have bought seven computers in six years. I suppose that's why (Microsoft founder) Bill Gates is rich, and Underwood is out of business."
Rooney was also self-deprecating, particularly in his last CBS appearance.
"I spent my first 50 years trying to become known as a writer and the next 30 trying to avoid being famous," he said. "I walk down the street or go to a football game and people shout, 'Hey Andy." I hate that."
Rooney is survived by four children. His wife of 62 years, Marguerite died of a heart attack in 2004, the network said.
Funeral details weren't immediately released.