Omar bin Yahya bin Ibrahim al-Barkati was tried and convicted of incest, the interior ministry said in a statement carried by the official Saudi Press Agency.
"He was executed as punishment for his crime and as a lesson to others," the ministry said, adding that authorities carried out the sentence in southwestern Asir region.
In a separate case, Yassir bin Hussein al-Hamza was executed in northwestern Jawf region after his trial and confession for smuggling amphetamine pills, the ministry said.
A third convict, Latif Khan Nurzada, a Pakistani, was executed for trafficking heroin into the kingdom. He was executed in the Muslim holy city of Mecca, the ministry said in another statement.
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According to an AFP tally, their executions bring to 16 the number of Saudis and foreigners put to death this year under the kingdom's strict version of Islamic sharia law.
Four have been executed since King Salman took office last Friday after the death of his predecessor Abdullah.
Under Abdullah, the number of executions jumped from 27 in 2010 to around 80 annually, with 87 last year.
The oil-rich Gulf Arab state faces constant international criticism over its human rights record, including the use of the death penalty.