Walsh died Dec. 5 of congestive heart failure in Monterey Park, Calif., The Los Angeles Times reported Wednesday.
Walsh was the voice of Los Angeles radio station KNX-AM from 1952 to 1986, but the rest of the country knew him as the announcer for "Gunsmoke," the Times said.
He opened the radio series starring William Conrad starting in 1952 with the words: "Around Dodge City and in the territory out West, there's just one way to handle the killers and the spoilers, and that's with a U.S. marshal and the smell of 'Gunsmoke.'"
Walsh moved with the series from radio to TV in 1955 with James Arness playing Marshal Matt Dillon.
Walsh was also the voice of Smokey the Bear, warning the public, "Only you can prevent forest fires."
He is survived by his wife of 49 years as well as three daughters, two brothers, two sisters, five grandchildren and one great-grandchild.