Sant Adrià de Besòs (Catalan pronunciation: [ˈsant əðɾiˈa ðəɫ βəˈzɔs]) is a city in the comarca of the Barcelonès in Catalonia, northern Spain. It is situated at the mouth of the river Besòs, extending to both sides of the estuary. The original settlement with the parish church is on the left bank of the river, in the north of the municipal territory. The municipality is now a collection of residential and, especially, industrial zones, integrated with the city of Barcelona.

The origins of the town are linked to the parish church of Sant Adrià, which was referred to in 1012, where in about 1092 a priory of Augustinian monks, dependants of Sant Ruf d'Avinyo, was founded. Saint Olegarius (San José María de Porcioles) came to this priory from 1095 to 1108 before becoming the bishop of Barcelona and, later, the archbishop of Tarragona. In 1127 the priory was moved to Santa Maria de Terrassa. Surrounding this church, upon a small hill fourteen metres high, to the west of the River Besòs, is the nucleus of the original village.

Currently, Sant Adrià is a town dominated by the service industry, but with a diverse manufacturing sector (especially in the areas of metal-work, chemistry, and construction) consisting mostly of medium-sized companies.