State media also reported that another 20 people had been charged in relation to the deaths of 18 people in the riots.
Last month, 21 people were convicted for their roles in the unrest, with 12 sentenced to death.
The worst ethnic violence in the region in decades broke out after ethnic Uighurs attacked Han Chinese during streets protests against an earlier attack on Uighur workers at a factory in southern China that left two dead.
In September, a series of alleged needle stabbings by Uighurs stoked fresh protests led by Han Chinese.
"We don't think they got a fair trial, and we believe this was a political verdict"
Dilxat Raxit, a Uighur activist based in Germany, condemned the executions as politically motivated.
"We don't think they got a fair trial, and we believe this was a political verdict," Raxit, a spokesman for the World Uighur Congress.
"The United States and the European Union did not put any pressure on China or seek to intervene and for that we are extremely disappointed."
Energy-rich Xinjiang, strategically located in central Asia, has been struck in recent years by bombings, attacks and riots, which Beijing blames on Uighur separatists.
The estimated eight million Turkic-speaking Uighurs have long complained of religious, political and cultural oppression by Chinese authorities, and tensions have simmered in Xinjiang for years.
Many Uighurs also resent the massive influx of Han Chinese settlers who have in some areas reduced them to a minority in their own land.
Rights groups and Uighur activists have accused Beijing of grossly exaggerating the threat from separatists to justify harsh controls.