"Termination of the services of General Abdul Rahman bin Saleh al-Bunyan, Chief of Staff," the official Saudi Press Agency (SPA) said, adding that Fayyad al-Ruwaili had been appointed as his replacement.
The monarch also replaced the heads of the ground forces and air defences.
No official reason was given for the changes, but they come as the kingdom's bloody conflict with Yemen's Huthi rebels nears the end of its third year.
Crown Prince Mohammed bin Salman, the heir to the throne and the son of the monarch, is the country's defence minister and has been consolidating his grip on power in recent months.
Disclaimer: No Business Standard Journalist was involved in creation of this content
