MBS is already de facto ruler of the Saudi kingdom, and the appointment formalizes his role as leader of the kingdom’s government.
The crown prince previously served as deputy prime minister as well as defense minister. He is being replaced as defense minister by his younger brother, Khalid bin Salman, who was deputy defense minister.
The royal decree reaffirmed all the other senior ministers in their posts, including Foreign Minister Prince Faisal bin Farhan Al Saud, Finance Minister Mohammed al-Jadaan and Investment Minister Khalid al-Falih.
By appointing MBS as prime minister, a role previously – and typically – held by the king, the 86-year-old monarch continues a slow but steady transfer of power in the kingdom.
The royal decree on Tuesday did not state the reasons behind the appointment, but the state-run news agency SPA said that the king – who remains head of state – will continue to chair cabinet meetings he attends.
In May, the king was hospitalized for medical examinations and treatments, SPA reported at the time.
The 37-year-old crown prince was already in charge of many of the kingdom’s major portfolios, including the economy, defense, oil, and internal security.