[10] Haitham is married to Sayyida Ahad bint Abdullah bin Hamad Al Busaidiyah and together they have four children.

[24] According to Omani state TV, Qaboos's letter was opened by the Defence Council and his identity was announced shortly thereafter.

This made his eldest son, Sayyid Theyazin, the country's first crown prince,[33] and officially formalised the method of succession.

He also changed the Basic Law of Oman to grant citizens and residents freedom of expression and opinion, removed a law that allowed the state to monitor private phone conversations, social media or postal correspondence, and granted the freedom to practice religious rites according to recognised customs provided it does not violate the public order or contradict morals.

[34] In April 2021 Oman introduced its value added tax, later than the United Arab Emirates, Saudi Arabia and Bahrain but before Qatar and Kuwait.

[37][36] Haitham's visits to Saudi Arabia, Qatar and the United Kingdom have been seen as a move to maintain peaceful and cordial relations with Oman's important partners.

[39] In September 2022, following Elizabeth II's death, Haitham visited Buckingham Palace to offer his condolences to King Charles III.

[40] He visited Tehran in May 2023 where he discussed regional diplomatic and security issues, two days after Muscat mediated a prisoner swap between Iran and Belgium.