The move wasn't totally unanticipated as a possibility, but has far-reaching consequences.
Despite his ambitions, Mohammed bin Salman has faced criticism for the Saudi-led war in Yemen, which has failed to dislodge Iranian-allied rebels known as Houthis from the Yemeni capital, Sanaa, and has had devastating effects on the impoverished country. He had, however, been reported intermittently to be in very poor health.
Even as deputy crown prince, Mohammed bin Salman had been amassing powers ever since his father took the throne. Prince Mohammed bin Nayef nominated Prince Mohammed bin Salman and received support from the majority of the council's members. Some of the reformd that are now being implemented are the upcoming IPO by the country's oil giant Aramco and Vision 2030 plan which have all been driven by Mohammed bin Salman.
"In a call with Qatari Emir Tameem Bin Hamad Al Thani, the President offered to help the parties resolve their differences, including through a meeting at the White House if necessary", said a White House statement.
The website of English-language news agency Press TV ran a lengthy article that denounced Mohammed bin Salman's hand in policy, including the "bloody military campaign" in Yemen and the "extensive and jarring economic shake-up" now underway in Saudi Arabia.
"We do not expect to see any major changes to key areas of policy, including economic-Prince Mohammed bin Salman has already been driving the economic agenda and the push to transform and liberalize the economy", said Monica Malik, chief economist at Abu Dhabi Commercial Bank.
Then-crown prince Abdullah bin Abdulaziz was the most important person in the kingdom for years after his brother King Fahd had a stroke in 1995, although Abdullah did not become king until a decade later. I used to talk about 70 being young for a Crown Prince in Saudi Arabia.
"The change is a huge boost to the economic reform programme..."
McDonald's KSA, which stands for Kingdom of Saudi Arabia, is a franchise operation which is owned by Riyadh International Catering Company.
Although Mohammed bin Salman's promotion to crown prince had always been expected among those who follow the royal family closely, the timing was a surprise, and puts the kingdom's future in relatively untested hands.
The new succession lineup and the sidelining of the former crown prince settles the competition between the two men. "There is no question as to who is going to be in charge", he said.