The Senate voted by a two thirds majority on Thursday to pass the Trade Promotion Authority Bill , which gives so-called 'fast track' powers to the president.
Mr Bush is now close to clinching presidential trade negotiating powers that eluded his predecessor. Congressional Republicans voted not renew the 'fast track' authority in 1994.
However, President Bush's decisions on trade policy have triggered rows with the European Union and other allies, who accuse him of protectionism over steel tariffs and farm subsidies.
Trade battles
The US president said the Senate decision to extend his powers "sends an important signal to our trading partners that we are committed to free and open trade."
Trade issues are controversial in the US, where labour unions argue free trade agreements with Mexico and China have put US jobs at risk.
The issue boiled over in Seattle in 1999 as labour and environmental protestors fought police at a meeting of world trade ministers.
The following year, President Bill Clinton fought an uphill battle to unite his own Democratic Party to support a more open trade relationship with China.
The bill passed by the Senate takes account of these concerns by offering aid to workers in industries threatened by imports or factory relocations abroad.
Concessions
"It's a landmark bill because it not only modernizes our trade policy but it also is balanced with a quite progressive trade adjustment assistance to Americans who are dislocated on account of trade," said Senator Max Baucus, Democrat chairman of the Senate Finance Committee.
"(The bill) empowers our nation to get the best bargain we can at the negotiating table," said Republican Senator Charles Grassley.
Mr Bush is in Moscow where he is due to begin talks on Friday with Russia's President Vladimir Putin which will include the issue of Russia's market reforms and oil exports.