Clearing the last hurdle before an historic step for the Nordic country whose neutrality lasted through two world wars and the Cold War.
Hungarian Prime Minister Viktor Orban addressed parliament before the crucial vote:
"The Swedish-Hungarian military co-operation and Sweden's accession to NATO will strengthen Hungary's security."
Stockholm abandoned its non-alignment policy for greater safety within the North Atlantic Treaty Organization in the wake of Russia's invasion of Ukraine in 2022.
Though Sweden was kept waiting in its bid to become a NATO member as Turkey and Hungary raised objections.
They both maintain better relations with Russia than other members of the U.S.-led alliance.
Turkey withheld ratification on Sweden's membership demanding tougher action against militants from the Kurdistan Workers' party or the PKK, that it said had made a home in Sweden. The PKK has been designated a terrorist group by Ankara.
Sweden changed its laws and relaxed rules over arms sales to assuage Turkey.
Hungary's foot-dragging was less clear in nature.
Budapest mostly vented its annoyance over Swedish criticism of the direction of democratic development under nationalist Prime Minister Orban, rather than making any concrete demands.
The accession of Sweden and Finland is the most significant expansion of the alliance since its move into Eastern Europe in the 1990s.
Robert Dalsjo is a senior analyst with the Swedish Defense Research Agency.
"NATO gains a member that is serious and capable and it removes a factor of uncertainty in Northern Europe. The final piece of the puzzle falling into place, making NATO's position in the Nordic-Baltic region whole."
Sweden will bring resources such as cutting-edge submarines tailored to Baltic Sea conditions and a sizable fleet of domestically produced Gripen fighter jets into the alliance.
It is hiking military spending and should reach NATO's threshold of 2% of GDP this year.
