Flights to Helsinki will connect with domestic Lapland services to Rovaniemi, Kittila and Ivalo.
The capacity boost will see more services on the Heathrow to Helsinki route from 27 November and additional frequencies from Manchester and Dublin to Helsinki from 3 December.
From 27 November, the carrier will also introduce a new weekend service, departing Helsinki for Heathrow every Saturday evening and returning to the Finnish capital on Sunday morning.
London-Helsinki will also see the reintroduction of twin-aisle aircraft from December, with Airbus A330s and A350s on certain flights.
In addition, Finnair will increase its services from Manchester and Dublin over the seasonal holidays. Between 3 December and 17 December, both routes will benefit from an additional return flight on a Friday. This extra service will also operate on 7 January 2022.
The route from Helsinki to Edinburgh will continue to be served three times a week.
Andrew Fish, Finnair general manager UK, Ireland & Benelux, said: “We’re excited to continue our recovery and re-establish our popular frequencies from the UK and Ireland in line with customer demand for flights to Finland over the festive season.”