When Finland becomes the military alliance's 31st member on Tuesday it will complete the fastest accession process in the organisation's history.
A new flagpole awaits the Finnish flag at NATO headquarters in Brussels.
When the Nordic country becomes the military alliance's 31st member on Tuesday it will complete the fastest accession process in the organisation's history.
Nato chief Jens Stoltenberg has welcomed the new arrival.
"It will be a good day for Finland's security, for Nordic security and for NATO's as a whole," he said. "Sweden will also be safer as a result."
Although weekend elections mean Finland looks to have lost Left-wing Prime Minister Sanna Marin who had championed her country's NATO membership - support for membership has been across the political board.
An asset for NATO
Russia's invasion of Ukraine triggered Finland's application along with that of Sweden.
Turkey had delayed the process, complaining that Finland was supporting "terrorists".
Sweden's is still being blocked by the Turkish government over similar complaints.
NATO sees Finland's membership as an asset. It shares a 1,340-kilometre border with Russia and unlike most members of the alliance, Finland did not cut defence spending after the Cold War.
It has a well-trained large army and has maintained a high level of readiness.
Russia has warned it will bolster its own forces along the Finnish border in case of a deployment of NATO troops.