The Cathedral has beautiful stained glass windows, sent to be made between 1883 and 1920, in London workshops representative of the Gothic-Renaissance style. These pour light and life within the Church, as well as decorate all of the walls. The Baptistery is surrounded, too, by three windows with their respective stained glass windows, that allow the afternoon and evening light to illuminate the Church.
The altar is illuminated from behind by three stained glass windows depicting the life of Saint Paul, patron of the Church.
The stained glass windows on the lateral walls picture different spiritual messages. All of these were sent to be made, and donated, by the most representative families of the British Community of those years, either in an individual or collective manner, in memory of loved ones. The technical quality of these works stand out as an example in Chile.