State-run China Central Television (CCTV) identified the man as Murzahti, 19, who slashed innocent men playing games in the remote city of Hotan a week ago, wounding four.
His two accomplices, Abduzahir and Abdughappar, later died from serious injuries after civilians fought back.
Abduzahir was the ringleader of the gang, according to the narrator of the interview.
Murzahti, who appeared on television in prison vest and had his hands cuffed, said Abduzahir told him "those who wage a holy war and die for it will not be judged after his death and will go directly to heaven."
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"I was scared when people fought back. I did not expect them to fight back. They hit us with desks and chairs in the room..."
He said: "When we tried to run, more people ran towards us with sticks. I thought we had no chance to escape."
Murzahti said he was sorry for carrying out the attack.
"I am still alive. If I could be released, I would never do the same again. I would stay at home and take care of my parents."
Murzahti said he and his accomplices surveyed the games room from the outside for about 90 seconds before moving in to attack. The video footage showed Murzahti waving an axe towards a woman in the games room.
Four civilians were injured in the attack.
In recent years, Xinjiang, home to native Muslim Uygurs, has witnessed violent attacks mostly from Islamist militants on civilians -- a departure from their previous targets of government offices and officials. The region has been restive over increasing settlements of Hans from other provinces.
Yesterday, police shot dead 13 assailants who rammed a truck into a police office building in Kashgar and set off explosives. Three officers were wounded.