Hussein Daghriri was executed in the southwestern province of Jizan after being sentenced to death for fatally stabbing fellow tribesman Nayef Daghriri in a dispute, the ministry said in a statement carried by the official SPA news agency.
His beheading brought to 49 the number of executions carried out in the desert kingdom this year, according to an AFP tally.
It came after UN independent experts called on Saudi Arabia yesterday to implement an immediate moratorium.
"The trials are by all accounts grossly unfair. Defendants are often not allowed a lawyer and death sentences were imposed following confessions obtained under torture."
Rape, murder, apostasy, armed robbery and drug trafficking are all punishable by death under Saudi Arabia's strict version of Islamic sharia law.