São João de Meriti is a municipality located in the state of Rio de Janeiro, Brazil. Situated within the Baixada Fluminense region, the city covers a total area of 34.996 km2. Historically, the municipality was known by the name São João do Rio Meriti.
As of 2022, the population of São João de Meriti was recorded at 440,962 inhabitants. Projections for the year 2025 estimate the population to reach approximately 466,503 residents.