Mohammed al-Otaibi was convicted of shooting dead another Saudi, the interior ministry said in a statement on the official Saudi Press Agency.
Authorities carried out the sentence in Riyadh.
Separately, Turki al-Zahrani was put to death in the Muslim holy city of Mecca for stabbing dead a fellow Saudi, the ministry said.
The two cases brought to 102 the number of Saudi nationals and foreigners executed in the kingdom this year.
That compares with 87 for all of 2014, according to AFP tallies, but is still far below the record 192 which rights group Amnesty International said took place in 1995.
“Saudi authorities have been on a campaign of death this year, executing more people in six months than all of the previous year,” Sarah Leah Whitson, Middle East and North Africa director of Human Rights Watch, said in a statement on Tuesday.
Echoing the concerns of other activists, the New York-based group said it has documented “due process violations” in Saudi Arabia’s judiciary that make it difficult for defendants to get fair trials even in capital cases.
Under the 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 punishment. -AFP