A spokesman for the Xinjiang government said the executions had been carried out after a review by the Supreme Court.
Uighur activist Dilxat Raxit condemned the executions, saying they were motivated by politics and the need to appease Urumqi's Han community.

A total of 21 people were sentenced in October. Nine were sentenced to death, and three were given the death penalty with a two-year reprieve, a sentence which is usually commuted to life in jail.
Tensions between the Uighurs and Han have been growing in recent years.
Millions of Han have moved to the region in recent decades, and while the majority of residents used to be Muslim Uighurs, Han now outnumber them in some areas, including Urumqi.
Many Uighurs want more autonomy and rights for their culture and religion - Islam - than is allowed by Beijing's strict rule.
According to a recent government white paper on Xinjiang, the July riots were caused by Uighur separatists promoting an independent "East Turkestan".
The exiled World Uighur Congress says Beijing exaggerates the threat to justify harsh controls.