The prime minister of Spain, officially the president of the Government (Spanish: Presidente del Gobierno), is the head of government of Spain. The prime minister nominates the ministers and chairs the Council of Ministers. In this sense, the prime minister establishes the Government policies and coordinates the actions of the Cabinet members. As chief executive, the prime minister also advises the monarch on the exercise of their royal prerogatives.

Although it is not possible to determine when the position actually originated, the office of prime minister evolved throughout history to what it is today. The role of prime minister (then called Secretary of State) as president of the Council of Ministers, first appears in a royal decree of 1824 by King Ferdinand VII. The current office was established during the reign of Juan Carlos I, in the 1978 Constitution, which describes the prime minister's constitutional role and powers, how the prime minister accedes to, and is removed from office, and the relationship between the prime minister and Parliament.

Upon a vacancy, the monarch nominates a candidate for a vote of confidence by the Congress of Deputies, the lower house of the Cortes Generales. The process is a parliamentary investiture by which the head of government is elected by the Congress of Deputies. In practice, the prime minister is almost always the leader of the largest party in the Congress, although not necessarily. The prime minister's official residence and office is Moncloa Palace in Madrid.

Pedro Sánchez, of the Spanish Socialist Workers' Party (PSOE), has been prime minister since 2 June 2018. He first came to power after a successful motion of no confidence against former prime minister Mariano Rajoy. Since then, Sánchez has led three governments, the most—along with Adolfo Suárez—just behind fellow socialist Felipe González, prime minister from 1982 to 1996. King Felipe VI re-appointed Sánchez for the third time on 17 November 2023 after he reached a coalition agreement with Sumar and gathered the support of other minor parties. His third government took office on 21 November 2023.

The Spanish head of government has been known, since 1939, as "President of the Government" (Spanish: Presidente del Gobierno).

Not only is this term confusing for English speakers because Spain is not a republic, but because the parliamentary speakers are also referred to as presidents of their respective chambers. For example, both President George W. Bush and his brother, Florida governor Jeb Bush, referred to José María Aznar as "president" on separate occasions, and Donald Trump referred to Mariano Rajoy both as "President" and "Mr. President" during Rajoy's 2017 White House visit. While this term of address was not incorrect, it could be misleading to English speakers so prime minister is commonly used as a culturally equivalent term to ensure clarity.

Use of the term "president" dates back to 1834 and the regency of Maria Christina when, styled after the head of government of the French July Monarchy (1830), the official title was the "President of the Council of Ministers" (Presidente del Consejo de Ministros). This remained until 1939, when the Second Spanish Republic ended. Before 1834 the figure was known as "Secretary of State" (Secretario de Estado), a denomination used today for junior ministers.

Spain was not unique in this regard: it was one of several European parliamentary systems, including France, Italy and the Irish Free State, that styled the head of government as 'presidents' of the government rather than the Westminster term of 'prime minister' (see President of the Council for the full list of corresponding terms). However the term 'president' is far older.