Royko began his newsman's career as a columnist for the Naval Air Station Glenview newspaper and the City News Bureau of Chicago before working at the Chicago Daily News as a political reporter, becoming an irritant to the City's Democratic Machine politicians with penetrating and skeptical questions and reports.
When the Daily News closed, Royko worked for its allied morning newspaper, the Chicago Sun-Times. In 1984, when Rupert Murdoch bought the Sun-Times, for whom he said he would never work: No self-respecting fish would be wrapped in a Murdoch paper and that, His goal is not quality journalism. His goal is vast power for Rupert Murdoch, political power. Mike Royko then worked for the rival Chicago Tribune. For a period after the takeover, the Sun-Times reprinted Royko's columns, while new columns appeared in the Tribune.
He died of a brain aneurysm at age sixty-four. His columns were syndicated country-wide in more than 600 newspapers, more than 7,500 columns in a four-decade career. He also wrote or compiled dozens of "That's Outrageous!" columns for Reader's Digest.
Many columns are collected in books; yet, his most famous book remains his unauthorized biography of Richard J. Daley, Boss, the best-selling non-fiction book portrait of Daley as corrupt and racist; it is a principal book about Mayor Daley and the City of Chicago under his mayoralty. On its publishing, the Mayor of Chicago forced 200 Chicago private bookstores to not stock Boss, but public demand for the book over-rode the Mayor, and book stores sold Boss; later, the Mayor's wife was caught vandalizing copies.
Like many columnists, Mike Royko created fictitious mouthpieces with whom he could "converse"; the most famous being Slats Grobnik, the epitome working class Polish-Chicagoan. Generally, the Slats Grobnik columns were two men discussing a current event in a Polish neighborhood bar. In 1973, Royko collected several columns as Slats Grobnik and Other Friends. Another of Royko's characters was his pseudo-psychiatrist Dr. I.M. Kookie (eponymous protagonist of Dr. Kookie, You're Right! ). Dr. Kookie, purportedly the founder of the Asylumism religion — according to which Earth was settled by a higher civilisation's rejected insane people — satirized pop culture and pop psychology.
Through his columns, Royko helped make his favorite after-work bar, the Billy Goat Tavern, famous, and popularized the curse of the Billy Goat. Billy Goat's reciprocated by sponsoring the Daily News's 16-inch softball team, and featuring Royko's columns on their walls.
The book Carl Erskine's Tales from the Dodgers Dugout: Extra Innings (2004) includes short stories from former Dodger pitcher Carl Erskine. Royko is prominent in many of these stories.
He was also fervently devoted to 16-inch softball and was inducted into the Chicago 16-inch Softball Hall of Fame shortly after his death, an honor Royko's family insists he would have considered as meaningful as his Pulitzer.
The "Royko Two Arrival" is an IFR arrival procedure at O'Hare International Airport.
Mike Royko is entombed in Acacia Mausoleum, Acacia Park Cemetery, Chicago.