The Radio-Canada television personality and longtime voice of the Montreal Canadiens was 82.
Premier Pauline Marois' office has announced in a statement there will be a "national commemorative ceremony" for Garneau's funeral.
That means the flag will be lowered to half-mast atop the Quebec legislature. The premier's office says more details will be released soon.
In a statement, Marois calls him "one of the most brilliant sports commentators of his era" and "a model for the generations inspired by him."
Garneau spent 23 years on the French-language CBC's version of "Hockey Night In Canada," in addition to working as a sports reporter since joining the network in 1957.
He was named to the Hockey Hall of Fame, awarded the Order of Quebec, wrote several books and covered nearly two-dozen Olympic Games as well as the Tour de France.