Congress completed work on the "emergency" spending bill when the Senate voted unanimously on Tuesday for a compromise measure, following passage by the House of Representatives last week.
Senate Appropriations Committee Chairman Thad Cochran, a Mississippi Republican, said the legislation was "of utmost importance to our troops who are deployed in the war on terror and for our allies in the world".
US President George Bush praised Congress for its bipartisan support of the measure and said he was looking forward to signing it.
"I appreciate the leadership in the House and Senate for working together to reach a final agreement that focuses taxpayer dollars on providing our troops and diplomats with the tools they need," Bush said in a statement.
Congress had been under pressure from the Bush administration to promptly approve the spending bill. Without the money, the Pentagon said, it would run out of funding for some war accounts by the middle of this month.
Of the $82 billion, $76 billion will go to the Pentagon to help it buy armour for soldiers and combat vehicles, ammunition, missiles and other war materials.
The money also will be used to increase death benefits for families of soldiers killed in combat.
While the Pentagon said the $76 billion would carry combat operations at least until 30 September, it has not said how much additional war funds will be needed beyond that date.
Millions on Iraq
The Bush administration will also get $592 million to build a new embassy in Iraq, set to be the largest US compound in the world.
The measure will provide more funding for training Iraqi security forces, which Massachusetts Democrat Senator Edward Kennedy said "is a key element of a successful strategy to stabilise Iraq and withdraw American forces".
Including the newly approved money, the United States will have spent nearly $300 billion since late 2001 fighting wars in Afghanistan and Iraq. About two-thirds of that was for Iraq.