Al-Kahachi said: "In the name of the people the court decided ... to sentence the convicted, Taha Yassin Ramadan, to death by hanging for committing the crime of willful killing as a crime against humanity."
New York-based Human Rights Watch had urged the court not to impose the death penalty, saying there had been a lack of evidence tying Ramadan to the Dujail killings.
"I was not assigned any mission in Dujail. All the witnesses confirmed they did not see me in Dujail," Ramadan told the court when asked if he had any final remarks before the ruling was delivered.
Louise Arbour, the UN human rights chief last week also urged the court to spare Ramadan's life, saying a death sentence would break international law.
If the ruling is upheld on appeal, Ramadan would be the fourth to face capital punishment after Saddam, his half brother and former intelligence chief Barzan Ibrahim, and Awad Hamed al-Bandar, former head of Iraq's Revolutionary Court, were sent to the gallows.