San Xoán de Poio monastery, Benedictine monastery in Poio, Spain.

San Xoán de Poio is a monastery in Poio, Pontevedra, with a Baroque church facade framed by two square bell towers and a lower stone wing with iron balconies. The church, begun in 1581, has a nave with barrel and rib vaults, three small chapels and a 1735 altarpiece with Solomonic columns. The rectangular cloister of the Oranges has three Tuscan levels, built 1747–1749.

The monastery was founded in the 7th century and gained importance during the Middle Ages through donations from nobles and monarchs. This ongoing support enabled expansion and transformation of the buildings across many periods.

The monastery is dedicated to Saint John the Baptist, whose image stands on the church portico, while the main altarpiece of 1735 shows the Virgin of Mercy, patron of the Mercedarian order, and Mercedarian saints from the Madrid convent. The old altarpiece commissioned from Bernardo Cabrera in 1631 was partly reused in the Christ chapel, which holds the Suevic-Visigothic tomb of Saint Trahamunda.

The complex is located in Poio and can be visited, with access to the church, cloisters, refectory, and various exhibition rooms. It is recommended to allow enough time to explore all areas thoroughly, as the site is extensive.

The monastery's hórreo, a large raised granary, stands after the monastic buildings; the sources give no further detail on its pillars or capacity. The museum occupies the cloister rooms, the old kitchen, the refectory and the chapter house, so the granary is seen from outside rather than entered.