Prince Mansour bin Muqrin, the deputy governor of Asir province, was returning from an inspection tour when his aircraft came down near Abha late on Sunday, the interior ministry said.
It did not give a cause for the crash.
The incident came hours after a major purge of the kingdom's political and business leadership.
An anti-corruption body led by Crown Prince Mohammed bin Salman, 32, ordered the detentions of dozens of people, including 11 princes, four ministers and dozens of ex-ministers.
Analysts see the unprecedented move as an attempt to cement the power of the heir to the throne.