The prime minister of Sweden (Swedish: statsminister, lit. "minister of state") is the head of government of the Kingdom of Sweden. The prime minister and their cabinet (the government) exercise executive authority in the Kingdom of Sweden and are subject to the Parliament of Sweden. The prime minister is nominated by the speaker of the Riksdag and is elected by the chamber by simple majority, using negative parliamentarianism. The Riksdag holds elections every four years, in the even year between leap years.

As with several other similar offices in Europe, the office of Prime Minister came into existence in the nineteenth century as a result of Sweden's democratisation. Prior to the creation of the office, Sweden had no official head of government separate from the king; the country in periods was an absolute monarchy. However, several figures had formerly attained de facto status as leader of the government. Today, the prime minister holds the most influential political role in Sweden.

Unlike most prime ministers in parliamentary systems, the prime minister is both de jure and de facto chief executive. This is because the Instrument of Government explicitly vests executive power in the government, of which the prime minister is the leader. The prime minister has two official residences; these are the Sager House and Harpsund.

Historically, the monarchy of Sweden served as both head of state and head of government. Examples like Kings Gustav I, Charles XI, and Gustav III showcase how the Swedish government was structured around the monarchy. However, many of these kings had powerful domestic advisors who sometimes took on the role of de facto head of government; the most prominent of these examples is Axel Oxenstierna, who played a pivotal role in the formation of the Swedish Empire. The office of Lord High Chancellor was commonly the closest role to a de jure head of government, and they had similar responsibilities to the modern Prime Minister during the so-called Age of Liberty; no governmental offices were called Prime Minister at the time.

At the adoption of the new Instrument of Government of 1809, the two offices of Prime Minister for Justice (Swedish: justitiestatsminister) and Prime Minister for Foreign Affairs (Swedish: utrikesstatsminister) were created, though their roles were no more than just the heads of their respective ministries. When the office of the prime minister was created in 1876, the prime ministers for justice and foreign affairs were thus subsequently demoted to Minister for Justice and Minister for Foreign Affairs. Unlike the minister for justice, the minister for foreign affairs did, however, continue to be styled as "Excellency", an honour shared only with the prime minister. After 1917, it was no longer possible for a monarch to appoint the prime minister and the councillors of state (cabinet ministers) at their own discretion, or keep them in office against the will of the Riksdag. From that time onward, while the king still formally appointed the prime minister, in practice he was required to appoint the leader of the majority party in the Riksdag, or the leader of the senior partner in the majority coalition. While the provision in the Instrument of Government stating that "the King alone shall govern the realm" remained unchanged, it was now understood that the king was required to exercise his powers through the ministers and act on their advice. Over time, the ministers came to de facto exercise the royal prerogatives. However, the Swedish term used for the government during this period was still Kungl. Maj:t, an abbreviation of Kunglig Majestät 'Royal Majesty'.

Until 1974, the executive authority in Sweden had been exercised through the King in Council. Constitutional reform provided a new Instrument of Government which de jure established the parliamentary system and created a cabinet government with constitutional powers not derived from the Crown. At the same time, it stripped the monarchy of even nominal political powers, making the cabinet the country's executive authority in both name and in fact. This codified a number of practices dating from the definitive establishment of parliamentary government in 1917.

The Instrument of Government requires that the prime minister appoint a member of the cabinet as Deputy Prime Minister, to perform the duties of the prime minister if the prime minister cannot. However, if a deputy prime minister is absent or has not been appointed, the senior minister in the cabinet becomes acting head of government. If more than one minister has equal tenure, the eldest assumes the position (see Swedish governmental line of succession for the present governmental line of succession).

Constitutionally, the prime minister's position is stronger than that of their counterparts in Denmark and Norway. Since 1975, the prime minister has been both de jure and de facto chief executive, with powers and duties specifically enumerated in the Instrument of Government. In the two neighboring Scandinavian monarchies, the monarch is the nominal chief executive, but is bound by convention to act on the advice of the ministers. However, the so-called Torekov Compromise reached in 1971 by the major political parties, codified with the Instrument of Government that went into effect in 1975, stripped the Swedish monarch of even a nominal role in governmental affairs, thus codifying actual practices that had been in place since the definitive establishment of parliamentary government in 1917.