The operator believes that the centralisation of these services will facilitate easy movement for travellers at the airport.
Car parking areas and the bus station will also be within close proximity of the terminal.
Commenting on the development, Finavia’s Helsinki Airport director Ulla Lettijeff said: “We are turning over a new leaf in the history of Helsinki Airport, as departing and returning passengers will henceforth be served in our new, magnificent terminal.
“Passengers will no longer need to think about which terminal they will depart from or arrive at.”
Terminals 1 and 2, as well as the corridor that links them, will be closed.
Finavia will also shutter the old departure and arrivals halls at the airport. These spaces will be converted into passenger and staff areas.
Lettijeff added: “The last time Helsinki Airport operated in one terminal was almost 30 years ago. At that time, the terminal in use was the first actual passenger terminal that opened in 1969 and was later expanded in 1983.”
The airport launched a new terminal for domestic flights in 1993.
In March, Finavia said that it will launch advanced security control technology at Helsinki Airport.
The technology will end the requirement for travellers to remove liquids and electronics from their hand baggage.