While nine militants were sentenced to death, three others received death penalty with a two-year reprieve, state-run Xinhua news agency reported.
Besides the death penalties, local courts in six cities in Xinjiang convicted 69 others in 23 terrorism-related cases and pronounced sentences ranging from life imprisonment to fixed-term imprisonment, a regional higher people's court said.
They were convicted for committing crimes of organising, leading or participating in terrorist organisation, intentional homicide, arson or illegal manufacture, storage and transportation of explosives.
The crimes were the focus of the region's special operation to crack down on terrorism, said the regional higher people's court.
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China blames the East Turkistan Islamic Movement (ETIM), an Al-Qaeda linked outfit, to the attacks in Xinjiang and in rest of China.
The ETIM, listed as terrorist group by UN, is fighting for the independence of Xinjiang, where native Muslim Uygurs deeply resent the increasing settlements of majority Hans from other provinces.
Militants also carried a number of knife attacks in different railway stations in China, prompting Chinese government to scale up security all over the country.
The sentences were announced as China which has launched a nationwide crackdown on militants from Xinjiang also firmed up plans with Pakistan to stop infiltration of ETIM militants from across the borders of Pakistan Occupied Kashmir (POK).