Rosoboronexport had provided weapons to the Syrian government.
"The American taxpayer should not be indirectly subsidizing the mass murder of Syrian civilians, especially when there are perfectly good alternatives for purchasing these same arms through US brokers," said Republican Sen. John Cornyn in a statement.
Cornyn authored the amendment as part of the National Defence Authorization Act.
Senators voted on the Cornyn amendment Thursday night. The entire defence authorization bill is scheduled to be voted on by the full Senate next week.
A similar defence appropriations bill, including barring Pentagon dealings with Rosoboronexport, has already passed the US House of Representatives.
Cornyn's amendment bars the use of American taxpayer funds to purchase goods - including helicopters to be flown in Afghanistan - from Rosoboronexport.
The company manages almost all of Russia's weapons sales, including supplies that have gone to both Syria and the US.
Through the firm, Russia has reportedly sold more than a billion dollars in weapons to Syria, including four cargo ships full of arms and three dozen combat jets.
Earlier this year the Pentagon announced a deal to purchase 10 helicopters for $171 million for use by the Afghan military.
"Continuing this robust business relationship with Rosoboronexport would continue to undermine US policy on Syria and US efforts to stand with the Syrian people," Cornyn said.
He and other members of Congress have long advocated an end to the weapons deals with Russia.
US President Barack Obama has threatened to veto the defence authorization bill for reasons unrelated to the Russian firm.
Washington: The US Senate has approved a measure that will end the ties between the Pentagon and Rosoboronexport, Russia's state-run arms exporter.
First Published: Saturday, December 01, 2012, 11:25