The Turkish parliament approved a bill on March 30 to allow Finland to join NATO, clearing the way for Helsinki to join the Western defence alliance as war rages in Ukraine.
The Turkish parliament was the last among the 30 members of the alliance to ratify Finland's membership after Hungary's legislature approved a similar bill earlier this week.
President Recep Tayyip Erdoğan said earlier in March that Finland had secured Turkey's blessing after taking concrete steps to keep promises to crack down on groups seen by Ankara as terrorists, and to free up defence exports.
Finland and Sweden asked to join the trans-Atlantic military alliance last year in response to Russia's invasion of Ukraine. But the process has been held up by Turkey and Hungary. The parliaments of all NATO members must ratify newcomers.
Turkey is still holding off approving the NATO membership bid of Sweden, which Ankara says has not gone far enough in cracking down on people Turkey considers terrorists. The three countries signed a pact on the issue last year.
The Turkish parliament's foreign affairs commission had unanimously approved the Finland bill last week. The Turkish legislative process was happening as it prepares for parliamentary and presidential elections on May 14.
Finland's membership would represent the first enlargement since North Macedonia joined the alliance in 2020.
Turkey has repeatedly said that Sweden needed to take additional steps against supporters of Kurdish militants and members of the network Ankara holds responsible for a 2016 coup attempt. Turkey treats both groups as terrorist organisations.
Talks between Sweden and Turkey have made little progress, especially following several disputes mainly over street protests by pro-Kurdish groups in Stockholm.
NATO Secretary-General Jens Stoltenberg has said he had urged Turkey and Hungary to ratify both applications. A vote on Sweden's bid has not yet been scheduled in Hungary.
The United States and other NATO countries are hoping that the two Nordic countries become members of the alliance at a NATO summit due to be held in July 11 in Lithuania's capital Vilnius.
Upon Turkish parliament's ratification of Finland's NATO membership, it is set to be approved by President Recep Tayyip Erdoğan and then published in the country's Official Gazette.
Finland has already completed the legal ratification process for its own part, in anticipation of its upcoming parliamentary election on Sunday and a corresponding electoral recess which could have otherwise postponed the process by some months.
Having completed the ratification process, both Turkey and Hungary need to send their approving documents to the U.S. government in Washington, which is the depository of NATO under the alliance's founding treaty.
Stoltenberg will then formally invite Finland to join NATO.
As a final step, Finland will deliver its "instrument of accession", a document signed by its foreign minister, with the U.S. government, the Finnish government said.
When Finland's instrument of accession document reaches the U.S. State Department, the Nordic country will formally become a NATO member.