The execution of Prince Turki bin Saud al Kabir is a rare death sentence carried out against a member of the kingdom's extensive royal family.
He had pleaded guilty to killing Adel al Mohaimeed in a brawl three years ago, according to officials.
Al Arabiya reported that the victim's family had refused blood money in exchange for the prince's life.
The Saudi interior ministry issued a statement in which it warned "whoever dares to commit such a crime that the Shariah penalty is awaiting".
It said "legitimate punishment would be the fate of whoever tries to assault innocent people and shed their blood".
The sentence was carried out in Riyadh.
The ministry did not specify how he was killed, but condemned people are often beheaded in public using a sword.
Saudi Arabia regularly carries out the death penalty but executions of royals - estimated to number several thousand - are rare.
The last one was in 1975 when Faisal bin Musaid al Saud assassinated his uncle, King Faisal.
