Considered Saddam's right-hand man, he was a member of the decision-making Revolutionary Command Council and regularly called upon to crush rebellion.
In March 1987, the ruling Baath party put him in charge of state agencies in the Kurdish area, including the police, army and militias.
As Iraq's eight-year war with Iran was drawing to a close, fighters from the rebel Patriotic Union of Kurdistan, with backing from Tehran, took over the farming community of Halabja near the border.
In March 1988, Iraqi swooped over Halabja, and for five hours they sprayed it with a deadly cocktail of mustard gas and the nerve agents Tabun, Sarin and VX.
An estimated 75 per cent of the 5,000 people killed were women and children, in what is now believed to have been the worst gas attack ever carried out against civilians.
New York-based Human Rights Watch has said al-Majid was responsible for the deaths or disappearances of around 100,000 non-combatant Kurds when he put down the revolt across the Kurdish region.
He said he ordered the attacks against the Kurds, who had sided with Iran in the war, for the sake of Iraqi security.
He refused to express remorse for the killings.
Two of the four death sentences he received, including the latest handed down on January 17, related to the so-called Anfal campaign against the Kurds.
Al-Majid had also been accused of displacing and killing about 2,000 clansmen of Massud Barzani, the Kurdish regional president.
After Iraqi troops swept into Kuwait in August 1990, al-Majid was named governor of the occupied emirate, which the regime considered Iraq's 19th province. As in the north, he swiftly and viciously annihilated resistance.
|The Halabja massacre is believed to be the worst gas attack ever against civilians [AFP]
Tens of thousands of people died when Saddam's forces, driven out of Kuwait by a US-led coalition after their 1990 invasion, put down the Shia uprising in a bloodbath that saw heavy shelling of southern Iraqi towns.
Al-Majid received his second death sentence in December 2008 for war crimes committed during this brutal crackdown.
His third death sentence came after al-Majid was convicted of crimes against humanity for orderin troops into Shia areas in 1999 to stop protests after the assassination of Mohammed Sadeq al-Sadr, a revered Shia cleric, after whom Sadr City is now named.
In January 2003, Ali left the country for the first time since 1988, visiting Syria and Lebanon in a bid to whip up regional support for Iraq.
He was thought to have been killed by coalition bombing of his villa in the southern city of Basra in 2003, but US officials were later forced to admit that he was still alive.