Saudi Foreign Minister Saud Al Faisal was sworn in on Monday before King Salman bin Abdel Aziz.
The Crown Prince and the Deputy Crown Prince were present.
"I swear by Almighty Allah to be loyal to my religion, King, and country, not to divulge a secret of the State's secrets, to maintain its interests and regulations, and to perform my duties with honesty, integrity and sincerity," he said.
Prince Saud was appointed as foreign minister in a new cabinet formed in January.