On 23 January 2015, Salman, aged 79, inherited the throne after his half-brother Abdullah died of pneumonia at the age of 90. The new king issued a statement which read "His Highness Salman bin Abdulaziz Al Saud and all members of the family and the nation mourn Custodian of the Two Holy Mosques King Abdullah bin Abdulaziz, who passed away at exactly 1 am this morning." He appointed his younger half-brother, Prince Muqrin, as the Crown Prince.
After coming to power, Salman reshuffled the cabinet on 30 January 2015. Khalid bin Ali bin Abdullah al-Humaidan was made the intelligence chief. Prince Bandar bin Sultan was removed from his post in the security council and the adviser to the monarch was also removed as were the former monarch's sons Turki as governor of Riyadh and Mishaal as governor of Mecca. Ali al-Naimi remained the minister of petroleum and mineral resources, as did Saud al-Faisal of the Ministry of Foreign Affairs and Ibrahim Al-Assaf as finance minister. Salman also "gave a bonus of two months' salary to all Saudi state employees and military personnel", including pensioners and students, while also asking citizens to "not forget me in your prayers".
In February 2015, he received Prince Charles during his six-day tour in the Middle East. They "exchanged cordial talks and reviewed bilateral relations" between the countries.
In March 2015, the king ordered the bombing of Yemen and military intervention against the Shia Houthis and forces loyal to former President Ali Abdullah Saleh, who was deposed in the 2011 uprising. He first put together a coalition of ten Sunni Muslim countries. Code-named Operation Decisive Storm, this was the first time the Saudi Air Force had launched airstrikes against another country since the 1990–91 Gulf War.
In April 2015, three months after becoming king, Salman appointed a full nephew, Muhammad bin Nayef, as the new Crown Prince to replace his youngest brother Prince Muqrin. Furthermore, he made his son, Mohammad bin Salman, the Deputy Crown Prince. Almost all powers under the king were concentrated in the hands of the crown prince and deputy crown prince, both of whom held the portfolio determining all security and economic development issues in Saudi Arabia.
In May 2015 the King Salman Center for Relief and Humanitarian Aid (KSRelief) was established to deliver aid internationally to victims of civil war and natural disaster, working with the UN and other agencies. As of June 2018, KSRelief has implemented more than 400 individual projects in 40 countries at a cost of $1.8 billion. Moreover, in 2018, KSRelief assisted 180,555 Syrian patients living in Zataari Syrian refugees camp in Jordan. In 2019, KSRelief signed a memorandum of cooperation with UNICEF that aims at enhancing cooperation in the humanitarian field, exchanging knowledge, sharing experiences, promoting voluntary work and boosting capacity building programs. Until 2019, the center provided 1,839 Yemeni civilians wounded during the war with prosthetic limbs for a total amount of $2.3 million.
In February 2015, a man from Hafar Al-Batin was sentenced to death for rejecting Islam. In June 2015, Saudi Arabia's Supreme Court upheld the sentence of 1,000 lashes and 10 years in prison for Raif Badawi, a Saudi Arabian blogger who was imprisoned in 2012 after being charged for 'insulting Islam'.
Prince Mohammad was his private adviser at the Ministry of Defense and at the Crown Prince Court. Mohammad was appointed as the Minister of Defense and head of the royal court upon his father's accession to the throne in January 2015. Turki bin Salman became the chairman of the Saudi Research and Marketing Group in February 2013, replacing his elder brother Faisal bin Salman.