It is the latest of several death sentences which activists say have been handed down since 2011 when demonstrations began among the minority Shiites.
A court in the capital Riyadh convicted the accused of firing five rounds from a pistol at a traffic police car on duty in the village of Awamiya, the Saudi Press Agency said.
He also fired on other officers who tried to stop him, it said.
In addition to weapons-related crimes the court found him guilty of offences including threatening and intending to communicate with groups wanting to cause “devastation,” SPA said.
“The court decided to pass the death sentence on the defendant for the crimes that he committed,” it said.
SPA did not name the accused or say when the crimes occurred.
Awamiya, just west of Dammam city, has been a focus for clashes between security forces and Shiite protesters.
In October protesters marched there in opposition to death sentences handed to Shiite religious leader Nimr al-Nimr and others, an activist said at the time.
Nimr was a driving force behind demonstrations against the Sunni authorities that erupted in 2011 in the oil-rich east, alongside a Shiite-led protest movement in neighbouring Bahrain. -AFP