The São João National Theatre is a theatre in the city of Porto, in Portugal. It is located in Batalha Square, in the historical centre of the city.
The history of the theatre begins in 1794, when the main authority of Porto, Francisco de Almada e Mendonça, encharged Italian architect Vicente Mazzoneschi with the project for an opera house. The original theatre was built between 1796 and 1798 and was named São João (St John) in honour of Prince-regent João, later crowned king as John VI of Portugal. The interior of the theatre was similar to São Carlos Theatre of Lisbon, built a little earlier.