Toronto-born Rabbi Howie Chaim Rotman, 55, had been in a coma since November 2014 after being critically injured in a small scale attack on a Jerusalem synagogue.
The Centre for Israel and Jewish Affairs says Rotman has died of his injuries almost a year after receiving wounds to his head, including a strike from a meat clever.
The attackers, killed by police in a shootout, were Palestinian cousins from East Jerusalem, Ghassan and Oday Abu Jamal.
The death toll from the siege has climbed to to six, including a police officer.
Rotman is survived by his wife and ten children.