The Dom Luís I Bridge (Portuguese: Ponte de Dom Luís I), or Luís I Bridge, is a double-deck metal arch bridge that spans the river Douro between the cities of Porto and Vila Nova de Gaia in Portugal. At its construction, its 172 metres (564 ft) span was the longest of its type in the world. It can be confused with the nearby Maria Pia Bridge, a railway bridge that was built 9 years earlier (and is located 1 kilometre (0.62 mi) to the east), which is similar in aspect to the Luís I bridge.

Today, the bridge's upper level is used by pedestrians and by line D of the Porto Metro, whilst the lower level is used by buses, taxis, cyclists and pedestrians. The lower level links to the Porto waterfront, including the Praça da Ribeira and the lower station of the Guindais Funicular, at its northern end, and to Gaia waterfront, with its Port wine lodges, at its southern end. The upper level connects to Porto city centre and São Bento station at its northern end, and adjoins the Serra do Pilar Monastery and the upper station of the Gaia Cable Car at its southern end.