Mohammed Ajmal Kasab, a Pakistani citizen, was one of 10 gunmen who rampaged through the streets of India's financial capital for three days in November 2008, killing 166 people.
Kasab was hanged in secrecy at 7:30 a.m. Wednesday at a jail in Pune, a city near Mumbai, after Indian President Pranab Mukherjee rejected his plea for mercy.
Union Home Minister Sushil Kumar Shinde said the home ministry sent Kasab's mercy plea to Mukherjee on October 16. Mukherjee rejected it on November 5, he said.
"It was decided then that on 21st November at 7:30 in the morning he would be hanged. That procedure has been completed today," Shinde said.
R.R. Patil, the home minister for the state of Maharashtra, where Mumbai is located, called the execution a tribute to "all innocent people and police officers who lost their lives in this heinous attack on our nation."
Indian authorities faced public pressure to quickly execute Kasab, and the government fast-tracked the appeal and execution process, which often can take years, or in some cases, decades.
Kasab and the other gunmen entered Mumbai by boat on November 26, 2008. Carrying mobile phones, grenades and automatic weapons, the gunmen fanned out across India's financial capital, targeting luxury hotels, a Jewish center and the city's main train station. The three-day attack was broadcast live on television, transfixing the nation and world.
Captured by a photographer striding through Mumbai's main train station, an assault rifle in hand, the baby-faced Kasab quickly became the iconic image of the siege.
India blames Laskhar e-Taiba, a militant Pakistani organization, for orchestrating the attacks. The incident inflamed relations between the nuclear armed neighbors.
An Indian judge sentenced Kasab to death in May 2010 for waging war against India, murder and terrorism, among other charges. Kasab cried that day as he heard the sentence.
Associated Press writer Aijaz Ansari in Mumbai and Chon Ngashangva in New Delhi contributed to this report.