They had been sentenced by a special "terrorism" tribunal in January of last year, in verdicts now upheld by the highest court, the Arryadh daily said.
The pair were convicted of shooting dead the French nationals -- one of whom was a teenager -- near the western city of Medina while they were on a desert excursion from their homes in the capital Riyadh.
Another 12 men convicted of helping the attackers were jailed for between three and 23 years.
Authorities in the kingdom set up specialised courts in 2011 to try dozens of Saudis and foreigners accused of belonging to Al-Qaeda or of participating in a wave of attacks that swept the country from 2003.
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The kingdom's current Crown Prince Mohammed bin Nayef oversaw a crackdown on the militants.
Arryadh also reported that a "terrorism" court in the Red Sea city of Jeddah sentenced eight Saudis to between one and 17 years for trying to establish an Al-Qaeda cell to carry out attacks.