The interior ministry had initially said the animal was a lion and deployed special forces to hunt down the beast which had been on the loose since the weekend flooding that killed at least 17 people.
But ministry spokeswoman Nino Giorgobiani later told AFP: "It was one tiger. It has been liquidated."
The attack came just two days after the country's prime minister said all the animals which were swept from the zoo in the flood -- including lions, bears and a hippo -- had been killed or captured.
Witnesses told Georgian television they saw a person being mauled by a white tiger near Heroes Square next to the zoo.
"It was a white tiger, a big one. It attacked a man, it seized him by the throat," one agitated witness told the Imedi channel.
The victim, a 43-year-old man, "was hospitalised with cardiac arrest and a severed carotid artery," the head of Tbilisi's Republican Hospital told AFP.
"The injuries were fatal, doctors were unable to restore his heart beat to save him," he said.