Spencer was born in Hughart, West Virginia, raised in Youngstown, Ohio, and moved back to Youngstown before he died. Spencer served with the 37th Infantry Division during World War II, during the Battle of New Georgia, on the USS Bougainville, and in the Philippines, for which he was awarded a Bronze Star. After the war, he lived for a while in Chicago where he was an avid fan of the Chicago Cubs. During the "Korean Emergency," he reenlisted in the military, this time in the Air Force.
Spencer did not begin writing until after he had a heart attack in his fifties, after which he read a couple of mystery novels which he found amusing. He taught himself to write his special brand of funny mystery novels, beginning with The Dada Caper (1978). David Merrick optioned five of his novels for Broadway, though they never saw the stage. The Chance Purdue series spoofed the private eye genre, and was written with one sentence paragraphs and minimal punctuation, with chapters prefaced by quotes from the fictional pundit Monroe D. Underwood.
Spencer was the author of fourteen novels starring hard-drinking Chicago private eye protagonists, including Lacey Lockington, Chance Purdue, Buzz Deckard, Luke Lassiter and Birch Kirby. One New York Times review described his writing as "including rat-tat-tat writing in which paragraphs are seldom more than one sentence...[and] the hero is a private eye who is always tailing the wrong people and hitting the wrong guys. Wild, shrewd mad and unexpectedly funny." and "Ross H. Spencer has, up until now, been published only in paperback books that demonstrated a wacky humor and an equally wacky writing style. In The Dada Caper (1978) and The Reggis Arms Caper (1979), Mr. Spencer got his style down mostly to one-sentence paragraphs. The prose hurtled along. Neither book was serious, but Mr. Spencer had fun spoofing the crime genre, and he did so with unusual expertise."