Although Rio has not registered any cases, it is close to where the disease has taken hold in neighboring Minas Gerais, Espirito Santo and Sao Paulo states.
The aim is "to expand the strategy of vaccination as a preventative measure," the Rio health department said in a statement.
The state government said it's aiming to vaccinate the whole population by the end of the year. A total of 12 million doses will be required, with three million already ordered, the statement said.
Brazil's health ministry says that yellow fever, which is carried by mosquitoes, has been confirmed in 352 cases, with another 915 under investigation in an unusually severe outbreak.
So far 113 deaths have been confirmed from the disease, with 104 more under investigation.
