File photo: Flags of member countries at the NATO headquarters in Brussels, Belgium. AFP
"Tomorrow we will welcome Finland as the 31st member," Stoltenberg told reporters on the eve of a historic meeting of NATO foreign ministers in Brussels.
The statement comes only a day after Finland's centre-right leader Petteri Orpo claimed victory in Sunday's general election, with the far-right Finns Party in second place ahead of Prime Minister Sanna Marin's Social Democrats in third.
Orpo's victory follows a visible shift away from left-wing politics in Europe with a breakthrough by nationalists in neighbouring Sweden and the far right's victory in Italy last year, Finland might become the latest country to join the nationalist wave in Europe.
The vote comes just days ahead of Finland's formal accession to the NATO defence alliance, made possible after Turkey ratified the country's membership bid on Thursday.
All 276 lawmakers present voted in favor of Finland’s bid, days after Hungary’s parliament also endorsed Helsinki’s accession.
Alarmed by Russia’s invasion of Ukraine a year ago, Finland and Sweden abandoned their decades-long policy of nonalignment and applied to join the alliance.
Full unanimity is required to admit new members into the 30-member alliance, and Turkey and Hungary were the last two NATO members to ratify Finland’s accession.
Sweden’s bid to join the alliance, meanwhile, has been left hanging, with both Turkey and Hungary holding out on giving it the green light despite expressing support for NATO’s expansion.
Turkey’s government accuses Sweden of being too lenient toward groups it deems to be terrorist organizations and security threats, including militant Kurdish groups and people associated with a 2016 coup attempt.
More recently, Turkey was angered by a series of demonstrations in Sweden, including a protest by an anti-Islam activist who burned the Quran outside the Turkish Embassy.
Hungary’s government contends some Swedish politicians have made derisive statements about the condition of Hungary’s democracy and played an active role in ensuring that billions in European Union funds were frozen over alleged rule-of-law and democracy violations.
Turkish officials have said that, unlike Sweden, Finland fulfilled its obligations under a memorandum signed last year under which the two countries pledged to address Turkey’s security concerns.