US President Joe Biden says his country will start sending fresh weapons and equipment to Ukraine within days.
Late on Tuesday, the US Senate approved a $95bn (£76bn) foreign aid package that includes military support for Israel and Taiwan as well as Ukraine.
Mr Biden vowed to sign it off "as soon as it reaches my desk" on Wednesday, so that aid can be sent "this week".
Ukraine has recently stepped up its calls for Western assistance as Russia makes steady gains in its invasion.
Included in the package is $61bn in military aid for Ukraine. It passed the Senate in a bipartisan vote of 79-18.
Tuesday evening's approval came after the measure passed the US House of Representatives on Saturday.
Mr Biden hailed its passage in a statement, calling it "critical legislation [that] will make our nation and world more secure as we support our friends who are defending themselves against terrorists like Hamas and tyrants like [Russian President Vladimir] Putin".
Democratic Senate Majority Leader Chuck Schumer said: "After more than six months of hard work and many twists and turns in the road, America sends a message to the entire world: we will not turn our back on you."
