News of the creator's death broke over Twitter when Watchmen illustrator Dave Gibbons offered confirmation from hospital sources.
"Reliable source confirms that Joe Kubert had been in hospital and has passed away. So sorry to hear this. A great artist and a great man," Gibbons wrote.
This was followed by a tweet from Richard Bruning, husband of Vertigo executive editor Karen Berger: "Joe Kubert one of the finest men I've ever known Rest in peace, Joe."
Kubert, who also plied his trade as a writer and teacher, is best known for his work on DC Comics' Hawkman, as well as his influential military titles such as Sgt Rock.
His two sons Adam and Andy, with whom he collaborated, are also celebrated comic book artists. Joe and Andy recently worked together on the high-profile Before Watchmen: Nite Owl title.
DC Comics will release the posthumous Joe Kubert Presents one-shot in October.