Municipal Chamber of Rio de Janeiro, Legislative building in Centro, Rio de Janeiro, Brazil.

The Municipal Chamber of Rio de Janeiro, seated in the Palácio Pedro Ernesto on Praça Floriano in Cinelândia, is the city's unicameral legislature. It has 21 members elected for four-year terms. The building, named after physician and mayor Pedro Ernesto, houses the debating chamber and offices; a move to the Edifício Francisco Serrador was planned.

The Municipal Chamber was founded with the city in 1566, initially with a procurator and a judge; the first election followed two years later. In 1808 King João VI created the intendente post, separating executive from legislative power, and in 1828 Pedro I restructured the chamber with nine councillors. Dissolved after the republic was proclaimed, it was reinstalled in 1977 with 21 members in the Palácio Pedro Ernesto, named after the physician and politician.

The building carries the name of a physician who served as mayor and championed improvements in public health. Visitors can explore the spaces and see how these social concerns shaped the building's design and current displays.

The building sits on Praça Floriano in the downtown area and is easy to reach on foot. Visitors can attend public sessions when they take place, so checking session times in advance is helpful for planning a visit.

The Chamber has been installed in the Palácio Pedro Ernesto, on Cinelândia, since 1977, after the 1976 election returned just 21 members. In December 2022 the Mesa Diretora bought the Edifício Francisco Serrador, also on Cinelândia, for R$ 149.6 million to serve as the new seat, with works budgeted at R$ 74 million after the TCM cut R$ 10.2 million.