The beheading of Saad bin Abdullah al-Jadid, who had shot dead fellow Saudi Abdullah bin Faraj al-Gahtani, took to 45 the number of executions since January 1, according to an AFP count.
His execution was reported by the official SPA news agency, citing an interior ministry statement.
Rights group Amnesty International says the country has regularly been among the world's top five executioners and is "well on track" to far exceed previous annual records for executions.
Rape, murder, apostasy, armed robbery and drug trafficking are all punishable by death under Saudi Arabia's version of sharia Islamic law.