Ankara on Saturday sent the formal accession protocol that states Sweden's membership to NATO is approved by Türkiye to U.S. authorities in Washington, according to official sources.
After more than a year of delays, Parliament ratified Sweden's bid on Tuesday and President Recep Tayyip Erdoğan signed the formal accession protocol on Thursday.
Sweden and Finland dropped decades of military non-alignment and applied for NATO membership in response to Russia's invasion of Ukraine nearly two years ago.
Finland became the 31st nation of the alliance last April.
NATO membership applications require unanimous ratification by all alliance members.
On the other side, Sweden's Prime Minister Ulf Kristersson said Friday he would "not negotiate" with Hungary over Sweden's NATO bid despite Budapest now being the sole holdout after Türkiye's ratification.
Hungarian Prime Minister Viktor Orban invited Kristersson to Budapest to discuss the issue "at your earliest convenience," an invitation Kristersson accepted on Thursday.
"I'm happy to go to Budapest ... We have a lot to talk about ... but we're not negotiating the NATO membership, there are no negotiations on this," Kristersson told Swedish television TV4.
"But we could talk about how we will best cooperate in NATO," he said.
On Tuesday, Swedish Foreign Minister Tobias Billstrom said there was "no reason to negotiate" with Hungary.
Kristersson said Friday that while he was willing to travel to Budapest, a meeting with Orban at the European Union Council in Brussels on Feb. 1 was more practical.
"We'll see each other on Thursday next week at the European Council and we can begin discussing things then," he said.
For a visit to Budapest, "we'd have to find a date for this; things like this aren't usually done in haste. I suspect that his calendar, like mine, is quite full."
Orban's invitation came just days after Hungary criticized Sweden for not taking steps to strengthen bilateral relations.
Budapest has often denounced Sweden's "openly hostile attitude," accusing Swedish representatives of being "repeatedly keen to bash Hungary" on rule-of-law issues.