Rep. Jim Moran, D-Va., sponsored the amendment, approved by a 407-5 margin, the House of Representatives Web site said.
"It is beyond unacceptable for the United States government to work with a firm that is arming the oppressive Syrian regime," Moran said.
"The United States does not condone the massacre of innocent men, women and children. Furthering contracts with Rosoboronexport contradicts our nation's commitment to the principles of freedom and democracy."
The vote Thursday on the amendment to the $606 billion defense spending bill came hours after Russia and China voted a third time against a U.N. Security Council resolution that would have authorized non-military sanctions against Syrian President Bashar Assad's regime if it did not withdraw heavy weapons and troops from urban areas within 10 days, RIA Novosti reported.
The Russian news agency said Rosoboronexport declined to comment on the vote Friday.
In the past year, the House Web site said, Rosoboronexport has supplied nearly $1 billion worth of arms to Assad's regime, including high-explosive mortars, sniper rifles, ammunition and refurbished attack helicopters.
The Defense Department acknowledged to Congress in March evidence exists showing Rosoboronexport's arms have been used by Assad's regime to kill Syrian civilians, the site said.
The House site said the Defense Department has procured 33 Mi-17 helicopters from Rosoboronexport for the Afghan Security Forces as part of a no-bid contract. The contract includes an order for 10 Mi-17s last week. Deliveries of those helicopters were due by 2016, RIA Novosti said.
In June, Russian President Vladimir Putin said Russian arms were not being used against pro-democracy protesters trying to oust Assad.
Frans Klintsevich, a Russian lawmaker and a member of the ruling United Russia party, predicted the U.S. ban on transactions with Rosoboronexport would be the first in a series of anti-Russia moves, RIA Novosti said.
"The U.S. is continuing to reshape the world, and Russia is the only thorn in its side in this process," Klintsevich said.
He called recent anti-Putin protests part of Washington's attempt to "split us up from within."