Saudi Arabia is a unitary absolute monarchy, along traditional Islamist lines, where the King is both the head of state and government. Decisions are, to a large extent, made on the basis of consultation among the King, the Council of Ministers, Islamic scholars (until the mid-2010s), tribal leaders, and other traditional elites of the society. Saudi government is authoritarian, although some analysts have characterized the government of Mohammed bin Salman as totalitarian. The Crown Prince and Prime Minister of Saudi Arabia, Mohammed bin Salman, is the de facto ruler of Saudi Arabia. Under his rule, he has centralized policymaking, purged competing political elites, and dismantled pre-existing power-sharing dynamics.

The Basic Law of Saudi Arabia contains many characteristics of what might be called a constitution in other countries. The Qur'an and the Sunnah is declared as the official constitution of the country. The kingdom's governance is officially proclaimed to be conducted on the basis of Islamic law (Shari'a). The Allegiance Council is responsible to determine the new King and the new Crown Prince. All citizens of full age have a right to attend, meet, and petition the king directly through the traditional tribal meeting known as the majlis.

The government is dominated by the vast royal family, the Al Saud, which has often been divided by internal disputes and into factions. The members of the family are the principal political actors allowed by the government. Political participation outside the royal family is limited. Saudi Arabia is one of only four countries (the other being Vatican City, Brunei, and Afghanistan) that does not have a separate legislative body.

Saudi Arabia is an absolute monarchy. According to the Basic Law of Saudi Arabia, the country's de facto constitution adopted by royal decree in 1992, the king must comply with Sharia (that is, Islamic law) and the Qur'an. The Qur'an and the Sunnah are declared to be the de jure country's constitution. There is no legally binding written constitution and the Qur'an and the Sunna remain subject to interpretation. This is carried out by the Council of Senior Scholars, the Saudi religious establishment, although the power of the religious establishment has been significantly eroded in the 2010s.

The government of Saudi Arabia is led byKing Salman, who acceded to the throne on 23 January 2015. No political parties or national elections are permitted, and according to The Economist's Democracy Index, the Saudi government was the eighteenth-most authoritarian regime among the 167 countries rated in 2022, being at it lowest score in 2012 and at its highest from 2020 to 2022. Government is dominated by the royal family.

The Basic Law specifies that the king must be chosen from among the sons of the first king, Abdulaziz Al Saud, and their male descendants subject to the subsequent approval of leaders (the ulama). In 2007, an "Allegiance Council" was created, consisting of King Abdulaziz's surviving sons plus a son of each of his deceased sons, to determine who will be the heir apparent (the Crown Prince) after the previous heir apparent dies or accedes to the throne. Prince Mohammad bin Salman is the current Crown Prince, and is widely regarded as the country's de facto ruler.

The king combines legislative, executive, and judicial functions and royal decrees form the basis of the country's legislation. Until 27 September 2022, the King also served as Prime Minister. On that date, a royal decree appointed Crown Prince Mohammed bin Salman as Prime Minister, while King Salman retained his role as head of state and continues to chair cabinet meetings he attends. He presides over the Council of Ministers (Majlis al-Wuzarāʾ), which comprises the first and second deputy prime ministers (usually the first and second in line to the throne respectively), 23 ministers with portfolio, and five ministers of state. The king makes appointments to and dismissals from the council, which is responsible for such executive and administrative matters as foreign and domestic policy, defense, finance, health, and education, administered through numerous separate agencies. There is also a 150-member Consultative Assembly, appointed by the King, which can propose legislation to the King but has no legislative powers itself, including no role in budget formation. The government budget itself is not fully disclosed to the public. "Fully 40%" ... is labeled 'Other sectors' (including defense, security, intelligence, direct investment of the kingdom's revenues outside the country, and how much goes directly to the royal family).

Although in theory, the country is an absolute monarchy, in practice major policy decisions are made outside these formal governmental structures and not solely by the king. Decisions are made by establishing a consensus within the royal family (comprising the numerous descendants of the kingdom's founder, King Abdulaziz). Also, the views of important members of Saudi society, including the ulama (religious scholars), leading tribal sheiks, and heads of prominent commercial families are considered.