The Senate voted 80 to 16 to authorize 48 billion dollars over the next five years -- 18 billion dollars more than Bush had requested -- for the program, which also includes funds to battle tuberculosis.
"This bill will expand American leadership on global health and foster hope around the world. Once fully funded, it will not only help poor countries but serve America's interests as well," said Paul Zeitz, executive director of the Global AIDS Alliance.
The legislation has provided a rare moment for the Democrats who control Congress to agree with the Republican president.
"We've been negotiating this legislation for many months and it is a product of bipartisan compromise and commitment to saving lives worldwide," Senator Joseph Biden, chairman of the foreign relations committee, said in a statement.
"I would also like to thank the President. His decision to launch this initiative was bold and unexpected and I believe historians may regard it as his finest hour," he said. "We will be proud to send this legislation to his desk."
The bill has already been approved by the House of Representatives.
Bush, who launched the program in 2003 with 15 billion dollars in funding, praised lawmakers for passing what he called "life-saving legislation."
The US leader said 50,000 people in sub-Saharan were receiving anti-retroviral treatment for HIV/AIDS when he launched the program in 2003. Today, 1.7 million people receive treatment around the world, he said.
"With passage of today's bill we are one step closer to ensuring that this excellent program continues to help those in need," he said. "I encourage the full Congress to move quickly to send me final legislation that I can sign."