In 1990, Chelios was traded to the Chicago Black-hawks. There, he expanded upon his reputation for rough defense, which had been cemented by an incident in a 1989 playoff game against the Philadelphia Flyers. Chelios elbowed Flyers player Brian Propp, driving his face into a metal bar holding up the glass around the rink. He was knocked unconscious, and a riot by Flyers fans nearly followed. However, Chelios was unapologetic. "I'm sorry he got hurt, but if he hit his head on the metal, that's just bad luck. I know I'm chippy, but that's when I'm most effective," he told Greenberg.
Chelios also gained notoriety for a thoughtless comment he made during the 1994 lockout, when NHL management refused to let the players play when the two sides could not agree on contract terms. Chelios, worried about his career and about the future of the sport, said to a reporter, "If I was [NHL commissioner] Gary Bettman, I'd be worried about my family, about my well-being right now. Some crazed fan or even a player, who knows, might take it into his own hands and figure that if they get him out of the way this might get settled." Chelios immediately regretted the comment, but it was too late.
In recent years, Chelios has attempted to tone down his aggression on and off the ice. "I want to be a role model for my kids," he told Sporting News reporter Larry Wigge in 1996. "I certainly don't want my … kids to come up to me or my wife, Tracee, and ask why daddy's such a mean guy." Still, Chelios maintains a tough streak. "He comes to win and he'll pay the price to win, whatever it is," Lou Lamoriello, who coached Chelios in the 1996 World Cup and the 1998 Olympics, told Sporting News reporter Helene Elliot. "That's something you don't teach. It has to be within a player."