In a brief announcement, the Indian Home Ministry said Indian President Pranab Mukherjee had rejected the clemency petition filed by Kasab, 24, on Nov. 5 and that the death sentence "was executed today at 7:30 a.m. at Yerawada Central Prison" in Pune, where he was taken from a jail in nearby Mumbai.
Last month the ministry rejected the clemency request and sent its report to Mukherjee for a final decision on whether to commute Kasab's death penalty.
Kasab was the lone survivor among 10 gunmen involved in the November 2008 attacks at various locations around Mumbai. The assault lasted three days and left 166 people, including foreigners, dead and more than 200 wounded. The other gunmen were killed by security forces during the siege.
Kasab and his partners reportedly chose Mumbai's busiest train terminus for the attack in which more than 50 were killed. The indiscriminate shootings had been caught on closed circuit television.
All 10 gunmen were reported to have reached Mumbai by sea from Karachi, Pakistan.
In upholding Kasab's death sentence, the Indian Supreme Court had said waging war against the country was his primary and foremost offense. The court dismissed his plea that he had been denied a fair trial and ruled that his confession, which he later recanted, was voluntary.
Describing him as a Lashkar-e-Toiba terrorist, CNN-IBN television, reported Kasab had been informed about his scheduled hanging on Nov. 12 and that Kasab asked that his mother living in Pakistan be informed about it.
The report quoted government officials that Kasab's family had been informed. The report said India also had informed the Pakistan Embassy in New Delhi about the hanging date.
Maharashtra Chief Minister Prithviraj Chavan was quoted as saying Kasab was buried on the premises of the jail where the hanging took place.
NDTV television quoted Indian officials that there had been no claim for the body from Pakistan.
"Kasab has been hanged to death today morning at Pune's jail. He was taken to Pune from Mumbai two days back. Kasab has been buried in Yerawada jail premises itself," Chavan said in the CNN-IBN report.
NDTV said Kasab's hanging was the first in India since 2004.
The execution came two days after India voted against a non-binding U.N. General Assembly draft resolution for abolishing the death penalty. India was one of 39 countries voting against it, while 110 countries voted for it.
Under Indian law, a death sentence can be given under a "rarest of rare" principle involving exceptionally heinous and cold-blooded murder cases.
The Mumbai attacks caused the already tenuous India-Pakistan relations to plunge, but of late both have been trying to mend their ties.
India has maintained that the LeT group in Pakistan had masterminded the attacks.