Itaguaí (Portuguese pronunciation: [itɐɣwɐˈi]) is a municipality located in the Brazilian state of Rio de Janeiro. Its population was 93,662 (2005) and its area is 272 km². The city was founded in 1688.
Itaguaí is located approximately 75 km west of the city of Rio de Janeiro on the road to Santos (SP). Its location between the shore of Sepetiba Bay and the Atlantic Rainforest offers great natural beauty.
The port of Itaguaí was opened in 1982. One of its main trading goods is alumina.
It serves also as dormitory town for workers of the industrial western zone (Zona Oeste) of Rio de Janeiro. It is the seat of the Roman Catholic Diocese of Itaguaí.