Pernambuco (/ˌpɜːrnəmˈb(j)uːkoʊ/ PUR-nəm-BEW-koh, -⁠BOO-, Brazilian Portuguese: [peʁnɐ̃ˈbuku] ^ⓘ, locally [ˌpɛʁ-]) is a state of Brazil located in the Northeast region of the country. With an estimated population of 9.5 million people as of 2024, it is the seventh-most populous state of Brazil and with around 98,067.877 km², it is the 19th-largest in area among federative units of the country. It is also the sixth-most densely populated with around 92.37 people per km². Its capital and largest city, Recife, is one of the most important economic and urban hubs in the country. Based on 2019 estimates, the Recife Metropolitan Region is seventh-most populous in the country, and the second-largest in northeastern Brazil. In 2015, the state had 4.4% of the national population and produced 2.8% of the national gross domestic product (GDP).

The contemporary state inherits its name from the Captaincy of Pernambuco, established in 1534. The region was originally inhabited by Tupi–Guarani-speaking peoples. European colonization began in the 16th century, under mostly Portuguese rule interrupted by a brief period of Dutch rule, followed by Brazilian independence in 1822. Large numbers of slaves were brought from Africa during the colonial era to cultivate sugarcane, and a significant portion of the state's population has some amount of African ancestry.

The state has rich cultural traditions thanks to its varied history and peoples. Brazilian Carnivals in Recife and the historic colonial capital of Olinda are renowned: the Galo da Madrugada parade in Recife has held world records for its size.

Historically a center of sugarcane cultivation due to the favorable climate, the state has a modern economy dominated by the services sector today, though large amounts of sugarcane are still grown. The coming of democracy in 1985 has brought the state progress and challenges in turn: while economic and health indicators have improved, inequality remains high.

The origins of the name Pernambuco are debated, though most hypotheses derive the name from the now-extinct Tupi language.

Some scholars claim that the name comes from the combining of the Tupi words para'nã, meaning "great river" or "sea" and buka, meaning "hole". Thus, pernambuco would mean "hole in the sea", possibly referring to the Canal de Santa Cruz on the Island of Itamaracá, north of Olinda, or to an opening in the reefs between Olinda and Recife. According to others, pernambuco was the name of brazilwood in local indigenous languages at the time of first contact, as the tree is found widely in the forests of the future state. A third hypothesis also derives from a Tupi word, paranãbuku, meaning "long river", a possible reference to the Capibaribe River, since primitive maps mark such a "Pernambuco river" north of Cabo de Santo Agostinho, south of Recife.

Another hypothesis, suggested by the academic Jacques Ribemboim, asserts the origins of the name from the Portuguese language. The Canal de Santa Cruz in Recife, at the beginning of the 16th century, was known as Boca de Fernão (named after the explorer Fernão de Noronha). The Indians may have pronounced Fernão as Pernao and reversed the order of the words, giving Pernão Boca or Pernambuka, leading to the contemporary name of Pernambuco.

The state also has some nicknames, such as Lion of the North, Land of Frevo and Maracatu and Blessed Land.