Saleh al-Zahrani was convicted of shooting dead Attiya al-Zahrani during a dispute between them, said the statement carried by the official SPA news agency.
The latest beheading in the southwestern Baha region brings to 115 the number of executions this year in the kingdom, compared with 87 for all of 2014, according to AFP tallies.
Rights group Amnesty International says Saudi Arabia is one of the world's most prolific executioners.
Under the conservative kingdom's strict Islamic sharia legal code, drug trafficking, rape, murder, armed robbery and apostasy are all punishable by death.
The interior ministry has cited deterrence as a reason for carrying out the punishments.
Rights experts have raised concerns about the fairness of trials in the kingdom.
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