The bill, if approved by US President Barack Obama, would grant a 10-year extension of the Iran Sanctions Act.
The US Congress has voted to extend sanctions against Iran for another 10 years in a development likely to renew tensions between Washington and Tehran.
The Senate voted 99-0 in favour of the measure on Thursday, a month after the House of Representatives unanimously approved the legislation. The measure will now head to President Barack Obama who, according to a White House official, is expected to sign it.
The Iran Sanctions Act (ISA), which imposes penalties on the country's energy, banking and defense industries, will expire on December 31 if not renewed.
Members of Congress and administration officials said the renewal of ISA would not violate the historic nuclear agreement with Iran reached last year. Under that deal, Iran agreed to scale back its nuclear programme in exchange for easing of sanctions on its finances and oil industry.
Last month, Iran warned that an extension to the sanctions would be a direct breach of the nuclear agreement and provoke a "reaction".
Congress' action, though, did not address the fate of the nuclear pact, which was opposed by every Republican in the Senate and House. Lawmakers said it would make it easier for sanctions to be quickly reimposed if Iran violated the deal.
Republican US President-elect Donald Trump strongly objected against the nuclear pact as he campaigned for the White House. Many other members of his party, which also controls Congress, have called for the new administration to tear up the agreement.