A photograph of Kasab wielding an assault rifle at the train station became the iconic image of the attacks. People outside the station set off firecrackers in celebration Thursday after the sentence was announced.
Judge M.L. Tahaliyani said Kasab "shall be hanged by the neck until he is dead." In rejecting Kasab's contention that he had committed the crime under duress and pressure from militants, the judge added: "Such a person can't be given an opportunity to reform himself."
The death sentence must be reviewed by the High Court. Kasab can also appeal the decision and apply for clemency to the state and central governments, though his lawyer said that no decision had been made yet on the next step.
Such motions often keep the convicted on death row for years, even decades, in India, which has not executed anyone since 2004. The special prosecutor in the trial, Ujjwal Nikam, said in an interview Wednesday that he expected it would take at least a year for the sentence to be carried out.
The November 2008 siege -- when ten young men armed with assault rifles attacked two luxury hotels, a Jewish center and a busy train station -- reverberated across India. Millions watched on television as the rampage turned into a siege on the hotels, while guests and staff hid.
Kasab was accused of the most lethal episode of the attacks -- when he and an accomplice killed and wounded dozens of people at one of Mumbai's busiest train stations.
"The judge has come to the most appropriate conclusion and it could send a positive message to anyone who would like to wage a war against India," India's External Affairs Minister S.M. Krishna told reporters in New Delhi.
India blames a Pakistan-based militant group, Lashkar-e-Taiba, for masterminding the attack, which has deepened the rift between the rivals.
There has been no public support and sympathy for Kasab in Pakistan during his trial, and official reaction to his sentencing was muted.
"We would appreciate that our legal experts need to go through the detailed judgment. At this stage, what I can tell you is that Pakistan has strongly condemned the horrific Mumbai attack. It is important that culprits are brought to justice," Pakistani Foreign Office spokesman Abdul Basit said.
Tahaliyani, the Indian judge, said that the evidence implicated at least 20 people -- many of them members of Lashkar living in Pakistan -- in a conspiracy to wage war against India.
Among them were top Lashkar leader Hafiz Muhammad Saeed -- whom Pakistan has yet to prosecute, much to India's ire -- and Zaki-ur-Rahman Lakhvi and Zarrar Shah, two other Lashkar operatives who are among seven men now on trial at a special court in Pakistan for their alleged role in the Mumbai attack.
Krishna, the external affairs minister, said India would keep pressing for the extradition of all those involved in the attacks.
Prime Minister Manmohan Singh of India and Prime Minister Yousuf Gilani of Pakistan met late last month on the sidelines of a regional summit in Thimphu, Bhutan, and agreed to resume peace talks that stalled after the Mumbai attacks.
The nearly yearlong trial into the 2008 attacks -- quick in a country where cases can drag on for decades -- had several twists and turns.
Kasab made a surprise confession in July, asking to be hanged and describing his training in Pakistan in vivid detail. He later retracted and made the bizarre claim that he had come to Mumbai seeking work in the city's prolific film industry and had been forced by the police to confess, an assertion the judge dismissed. He pleaded not guilty when his trial began.
Kasab's conviction and death sentence were welcomed in Mumbai. "They should hang him near the Gateway of India," said Ramesh Pawar, a bank employee, referring to the popular tourist attraction on the waterfront.
"We're all very satisfied," said Deven Bharti, a senior police official involved with the investigation into the attacks. "I hope it will be a deterrent for Pakistan, so they will stop exporting terrorists across the border."
Though India voted against a moratorium on capital punishment at the United Nations in 2007 and 2008, in practice, the country has been veering away from applying the death penalty.
Only one person has been executed since 1998 -- a man convicted of raping and murdering a 14-year-old girl, who was sent to the gallows in August 2004.
Many convicts simply wait, as bureaucratic disregard -- which some say is purposeful neglect by politicians leery of capital punishment -- effectively transmutes a death sentence into life in prison. People responsible for the 1991 assassination of former Prime Minister Rajiv Gandhi and a 2001 attack on India's Parliament have yet to be executed.
Officials from the Home Ministry said Wednesday that they didn't have information available on the number of Indians currently awaiting execution.