Faleh Bin Ali Al Otaibi was found guilty of forced incestuous sodomy, it said in a statement carried by the SPA state news agency, adding that he committed the act after drinking alcohol, banned in the kingdom.
The identity of the victim was not disclosed.
Al Otaibi’s beheading in the western city of Makkah brings to 53 the number of people executed in Saudi Arabia so far this year, according to an AFP tally based on official reports.
Rights group Amnesty International puts the number of people executed in the Gulf country last year at 79.
In addition to murder, the death penalty is handed down in Saudi Arabia for a wide range of offences including rape, apostasy, armed robbery and drug trafficking, as stipulated by Islamic Sharia law.