The Old Cathedral of Rio de Janeiro dedicated to Our Lady of Mount Carmel, (Portuguese full name: Igreja de Nossa Senhora do Monte do Carmo da antiga Sé, literally Church of Our Lady of Mount Carmel of the Ancient See) is an old Carmelite church which served as cathedral (Sé) of Rio de Janeiro from around 1808 until 1976. During the 19th century, it was also used successively as Royal and Imperial Chapel by the Portuguese Royal Family and the Brazilian Imperial Family, respectively. It is located in the Praça XV square, in downtown Rio. It is one of the most important historical buildings in the city.

When the Carmelite Order arrived in Rio in 1590, they settled in a small chapel near Guanabara Bay. During the 17th and 18th centuries, the order built a large convent and renovated the chapel, referred to as the Igreja de Nossa Senhora do Monte do Carmo (Church of Our Lady of Mount Carmel). Building of the present church started around 1761, and was probably directed by Portuguese architect Manuel Alves Setúbal. The church was consecrated in 1770, still with the façade unfinished. The inner decoration, in gilded woodwork in Rococo style, was carved after 1785 by master Inácio Ferreira Pinto, one of the main sculptors of 18th-century Rio de Janeiro.