He said the majority of members, which exceed three-quarters of those present, backed the appointment.
King Abdullah said Prince Muqrin would continue in his present position as second deputy premier.
The decree also stated that the king would have the right to propose his candidate to the Allegiance Council in future if he wanted to appoint a deputy crown prince and issue a royal decree for that appointment following the council's approval.
Prince Muqrin has held many important positions in the government, including director of intelligence and governor of Hail and Madinah.
He graduated with a degree in aeronautics from the Britain's RAF College in Cranwell in 1968 and also acquired a master's degree in military sciences.
He has also served in several positions in the Royal Saudi Air Force (RSAF) until 1980, when he was appointed as the governor of Hail.
