A fifteenth-generation descendant of the founder of the House of Al Said,[4] he was the longest-serving leader in the Middle East and Arab world at the time of his death,[5] having ruled for almost half a century.

His reign saw a rise in the country's living standards, the abolition of slavery, the end of the Dhofar Rebellion, and the promulgation of Oman's constitution.

After his death, the royal court named his intended successor, his cousin Haitham bin Tariq, as sultan.

[10] After graduating from Sandhurst in September 1962, he joined the British Army and was posted to the 1st Battalion The Cameronians (Scottish Rifles), serving with them in Germany for one year.

[11][12] After his military service, Qaboos studied local government subjects in England and then completed his education with a world tour chaperoned by Leslie Chauncy.

His personal relationships were limited to a handpicked group of palace officials who were sons of his father's advisors and a few expatriate friends such as Tim Landon.

Sultan Said said that he would not allow his son to be involved with the developing planning process, and Qaboos began to make known his desire for change—which was quietly supported by his expatriate visitors.

[11][additional citation(s) needed] Qaboos acceded to the throne on 23 July 1970 following a successful coup against his father, with the aim of ending the country's isolation and using its oil revenue for modernization and development.

[14] The coup was supported by the British, with Ian Cobain writing that it was "planned in London by MI6 and by civil servants at the Ministry of Defence and the Foreign Office" and sanctioned by the Prime Minister, Harold Wilson.

[15] The first pressing problem that Qaboos bin Said faced as sultan was an armed communist insurgency from South Yemen, the Dhofar Rebellion (1962–1976).

[11] Oman was a poorly developed country, severely lacking in infrastructure, healthcare, and education, with only 10 km (6 mi) of paved roads and a population dependent on subsistence farming and fishing.

[23] Qaboos' closest advisors were reportedly security and intelligence professionals within the Palace Office, headed by General Sultan bin Mohammed al Numani.

According to CBS News, 19 June 2011, Several protest leaders have been detained and released in rolling waves of arrests during the Arab Spring, and dissatisfaction with the state of affairs in the country is high.

In August 2014, The Omani writer and human rights defender Mohammed Alfazari, the founder and editor-in-chief of the e-magazine Mowatin "Citizen", disappeared after going to the police station in the Al-Qurum district of Muscat, only to be pardoned some time later.

[46] Nawwal was renamed Kamila at the time of her marriage and is the half-sister of Qaboos' successor, Haitham bin Tariq.

[51][52] On 14 December 2019, he was reported to be terminally ill from the disease after being admitted to the UZ Leuven hospital in Belgium, and opted to return home because he wanted to die in his own country.

The United Kingdom lowered flags to half-mast as a sign of respect, and Prime Minister Boris Johnson described Qaboos as a "father of the nation", and "an exceptionally wise and respected leader" who "sought to improve the lives of the Omani people" and contributed to the country's development "into a stable and prosperous nation".

Article 6 of the constitution says the Royal Family Council has three days to choose a new sultan from the date the position falls vacant.

Using same-generation primogeniture, the successor to Qaboos would appear to be the children of his late uncle Sayyid Tariq bin Taimur, Oman's first prime minister and the Sultan's former father-in-law.

[72][75] On 11 January 2020, Oman state TV said the Royal Family Council, in a letter to the Defense Council, had decided to defer to the choice that Qaboos named in his will, and thus had opened the letter by Qaboos naming his successor, announcing shortly that Haitham bin Tariq is the country's ruling sultan.