Staff noticed the posting around 1 a.m., but couldn't immediately fix it, the Canadian Broadcasting Corp. reported.
The article claimed 53-year-old Liberal Premier Jean Charest had died of a heart attack in a Montreal hospital, The (Montreal) Gazette reported.
Le Devoir editor-in-chief Josee Boileau told the Canadian Broadcasting Corp. the hackers blocked staff from accessing the site for 90 minutes. It was finally shut down around 2:30 until nearly 5 a.m., when an apology was posted.
"We offer our apologies, of course to the premier and to our readers," the newspaper's site said. "Le Devoir cannot comment further until the source of the problem has been identified."
A similar hacking prank happened in June when the federal Conservative Party's site falsely reported Prime Minister Stephen Harper had been rushed to an Ottawa hospital after choking on his breakfast.