Thousands of people had rallied against the deal.
Slovakia’s parliament has approved a controversial new defence treaty with the United States despite vocal protests.
The agreement will allow the US military to use two Slovak air force bases for the next ten years.
Slovakia will meanwhile receive $100 million (€87.4 million) to modernise the Malacky-Kuchyna and Sliac airbases.
The deal had been signed by US Secretary of State Antony Blinken and Slovakian defence minister Jaroslav Nad on February 3.
It was approved by 79 members of Slovakia's 150-seat parliament on Wednesday and is expected to be ratified by President Zuzana Čaputová.
The vote on the so-named "Defence Cooperation Agreement" was split between lawmakers from Slovakia four-party ruling coalition and the opposition.
Prime Minister Eduard Heger said the treaty would “significantly enhance" the NATO member's security.
The parliament vote took place amid fears that Russia is preparing to invade Ukraine after amassing more than 100,000 troops near its eastern border. Moscow has denied the Western claims.
But the treaty was fiercely opposed by many MPs, who claim it would compromise the country’s sovereignty and allow US troops to be permanently stationed on Slovak territory.
Thousands of people rallied against the treaty on Tuesday in front of the parliament building during the debate, some waving national flags and banners such as “Stop USA Army". Police prevented some protesters from entering the premises.
During the debate, some opposition MPs used whistles to prevent others from speaking and seized a Ukrainian flag unveiled by coalition lawmakers.
Some opposition lawmakers have even said that the treaty could lead to the possible deployment of nuclear weapons in Slovakia. Both the Slovak and US governments have rejected those charges.
“Nothing in [the] agreement creates permanent US bases or troop presence in Slovakia, and the agreement fully respects Slovakia’s sovereignty and laws,” Blinken said during the signing ceremony in Washington, DC.
The US has a similar agreement with 23 other NATO members, including Poland and Hungary, two other countries that --like Slovakia -- neighbour Ukraine.
The specific future deployment of US forces in Slovakia would still need the approval of Bratislava's government and parliament.