The Manueline (Portuguese: estilo manuelino, IPA: [ɨʃˈtilu mɐnweˈlinu]), occasionally known as Portuguese late Gothic, is the sumptuous, composite Portuguese architectural style originating in the 16th century, during the Portuguese Renaissance and Age of Discoveries. Manueline architecture incorporates maritime elements and representations of the discoveries brought from the voyages of Vasco da Gama and Pedro Álvares Cabral. This innovative style synthesizes aspects of Late Gothic Flamboyant architecture with original motifs and influences of the Plateresque, Mudéjar, Italian, and Flemish architecture. It marks the transition from Late Gothic to Renaissance. The construction of churches and monasteries in Manueline was largely financed by proceeds of the lucrative spice trade with Africa and India.

The style was given its name, many years later, by Francisco Adolfo de Varnhagen, Viscount of Porto Seguro, in his 1842 book Noticia historica e descriptiva do Mosteiro de Belem, com um glossario de varios termos respectivos principalmente a architectura gothica, in his description of the Jerónimos Monastery. Varnhagen named the style after King Manuel I, whose reign (1495–1521) coincided with its development. The style was much influenced by the astonishing successes of the voyages of discovery of Portuguese navigators, from the coastal areas of Africa to the discovery of Brazil and the ocean routes to the Far East.

Although the period of this style did not last long (from 1490 to 1520), it played an important part in the development of Portuguese art. The influence of the style outlived the king. Celebrating the newly maritime power, it manifested itself in architecture (churches, monasteries, palaces, castles) and extended into other arts such as sculpture, painting, works of art made of precious metals, faience and furniture.

This decorative style is characterized by virtuoso complex ornamentation in portals, windows, columns and arcades. In its end period, it tended to become excessively exuberant as in Tomar.

Several elements appear regularly in these intricately carved stoneworks:

When King Manuel I died in 1521, he funded 62 construction projects. However, much original Manueline architecture in Portugal was lost or damaged beyond restoration in the 1755 Lisbon earthquake and subsequent tsunami. In Lisbon, the Ribeira Palace, the residence of King Manuel I, and the Hospital Real de Todos os Santos were destroyed, along with several churches. The city, however, still has outstanding examples of the style in the Jerónimos Monastery (mainly designed by Diogo Boitac and João de Castilho) and in the small fortress of the Belém Tower (designed by Francisco de Arruda). Both are located close to each other in the Belém neighbourhood. The portal of the Church of Nossa Senhora da Conceição Velha, in downtown Lisbon, has also survived destruction.

Outside Lisbon, the church and chapter house of the Convent of Christ at Tomar (designed by Diogo de Arruda) is a major Manueline monument. In particular, the large window of the chapter house, with its fantastic sculptured organic and twisted rope forms, is one of the most extraordinary achievements of the Manueline style.

Other major Manueline monuments include the arcade screens of the Royal Cloister (designed by Diogo Boitac) and the Unfinished Chapels (designed by Mateus Fernandes) at the Monastery of Batalha and the Royal Palace of Sintra.