Zhao Liping, 65, was found guilty of murder, bribery and possession of firearms and explosives by a court in Taiyuan, the capital of the northern province of Shanxi, in November.
China's supreme court announced Friday that Zhao had been executed after it approved the sentence, according to the official Xinhua news agency.
China carries out executions by lethal injection or shooting, but the method used this time was not specified.
Zhao was detained in 2015 in Chifeng on suspicion of killing a 28-year-old woman with whom he "had an intimate relationship" because she wanted to expose his wrongdoings, Chinese media reported earlier.
Zhao headed the police in Inner Mongolia for seven years until he retired in 2012, and was also a deputy head of the regional People's Political Consultative Conference, a Communist-controlled debating chamber.
Many fallen Chinese officials have been found to have mistresses, and corruption investigations have often been triggered by allegations from spurned or angry women.
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