Alaa al-Zahrani was found guilty of killing fellow Saudi Abdullah al-Sumairi with a rock to the head, the interior ministry said.
He was put to death in the Red Sea city of Jeddah, said a ministry statement carried by the official SPA news agency.
The 70 executions so far this year include 47 death sentences for "terrorism" carried out in a single day on January 2.
Most people sentenced to death in Saudi Arabia are beheaded with a sword.
Amnesty International says the number of executions in Saudi Arabia last year was the highest for two decades.
However, the tally was far behind those of China and Iran.
The kingdom has a strict Islamic legal code under which murder, drug trafficking, armed robbery, rape and apostasy are all punishable by death.
