Ali al-Dabbagh, the spokesman for the Iraqi government, said Majid was executed Monday following a death sentence for crimes committed against the Kurdish population in 1988, the Voices of Iraq news agency reports.
"Ali Hassan al-Majid has been executed after all legal conditions were fulfilled," the spokesman said.
Majid served as the defense minister under Saddam. He was sentenced to death by hanging for orchestrating an attack on the Kurdish city of Halabja using Sarin and VX nerve gas.
It was his fourth death sentence since U.S.-led forces overthrew the Baath government of Saddam Hussein in 2003.
Kurdish leaders complained Majid's crimes against the Kurds should be labeled as an act of genocide. Majid never denied charges he ordered the gas attacks on the Kurds, considered the worst chemical weapons attack on a civilian population in history.
Meanwhile, Iraq's al-Sumaria news Web site said Mohammad Salman, an adviser to Iraqi Prime Minister Nouri al-Maliki, survived an assassination attempt when a roadside bomb exploded near his convoy north of Baghdad on Monday.
Three bomb blasts rocked several hotels in the capital city on Monday, killing at least 36 people.
Iraq is bracing for an uptick in violence as the country prepares for March parliamentary elections. Observers said it was a coincidence the bombings coincided with the Majid execution as such a coordinated attack likely needed elaborate planning.