Fischetti was born in New York City. In the 1920s, Fischetti and his two brothers, Joseph and Charles Fischetti moved to Chicago to join their first cousin Al Capone in the Chicago crime family. During this period, the Fischetti brothers alternated between driving for Capone, acting as his bodyguards, and distilling bootleg alcohol. After Prohibition ended, Rocco started running illegal gambling operations for the Outfit. In 1932, Rocco was acting as a bodyguard for John Capone, Al's brother, when the two men were arrested on the streets of Chicago for a minor offense.