The US Senate on Tuesday finally passed a bill guaranteeing financial support to the families of 9/11 first responders and victims — as a chorus of riotous cheers arose from the gallery.

Senators approved 97-2 “The Never Forget the Heroes: James Zadroga, Ray Pfeifer and Luis Alvarez Permanent Authorization of the September 11th Victim Compensation Fund Act” that was named for a trio of heroic NYPD and FDNY members who died from health complications caused by their work at Ground Zero.

It was a somber occasion for first responders, who cheered the bill but lamented their sickened comrades and the proposal’s slow slog through Congress.

“We are very proud of our brother. And we’re very proud that his name is on the bill. And we hope that he is resting in peace. And we hope this takes care of the many first responders,” Alvarez’s tearful brother Philip told The Post following the vote.

“We hope that not a penny of that money will ever need to be used — because if it’s used that means that somebody else gets sick, and we don’t want that,” he added.

“After this vote, the people in the gallery above us — these brave men and women who have suffered unbelievably — will not have to come here again,” said sponsor Kirsten Gillibrand (D-NY) before the vote was called, referring to the Senate gallery where families, including Alvarez’s, watched with bated breath.

“This should never have been a fight. It should never have taken this long to pass this bill and make it permanent. It should never have been a question,” she continued.

It was a fraught road for the bill, which received a major attention boost when former “The Daily Show” host Jon Stewart gave blistering testimony before a House panel in June that scorched lawmakers for not taking the reauthorization seriously.

He was joined by a cancer-stricken Alvarez — who spent his final days fighting for the bill’s adoption, but died before he could realize the hard-fought victory.

The measure cleared its first hurdle on July 12 when it overwhelmingly passed the House 402-12.

Then penny-pinching Republican Sens. Mike Lee of Utah and Rand Paul of Kentucky blocked a vote on the measure last week when they raised objections over the legislation’s cost and oversight.

An amendment introduced by Lee to limit the fund authorization to $10 billion for the first 10 years died on the Senate floor 32-66. Another amendment introduced by Paul to make cost-offsetting budget cuts elsewhere also failed 22-77, ahead of the full bill’s passage.

Lee and Paul were the two dissenting votes on the final bill’s passage.

“While I support our heroic first responders, I can’t in good conscience vote for legislation which, to my dismay remains, unfunded,” Paul said, citing the $22-trillion-and-growing national debt as he tried to explain his vote.

The act, which funds the compensation program through 2092, is expected to cost $10.2 billion over the first decade, however there is no cap on the program’s spending.

Stewart, who watched nervously from the gallery, pumped his fist in celebration when the Lee amendment failed.

The bill was adopted just days after the FDNY tallied its 200th 9/11 illness-related death. Firefighter Richard Driscoll died at 73 last Wednesday.

The victims’ fund — originally known as the Zadogra Act in honor of the slain NYPD officer — was first signed into law in 2011 after many first responders became ill from cancer and respiratory complications following their work at Ground Zero.

Congress reauthorized the fund in 2015 to accept claims through 2020.

So far about 22,500 people — including 850 who died — have received about $5 billion combined in settlements. Payments average $250,000 for eligible 9/11 victims suffering from cancer, with lower payments for less severe sicknesses.

But the funding was about to run out. With 21,000 pending claims and only about $2 billion left, the fund’s administrator announced earlier this year that future awards would be slashed by up to 70%.

The reauthorization ensures continued payments and would make whole the 9/11 first responders and others who were subjected to settlement cuts.

The passage will “guarantee once and for all that the heroes who rushed to the towers 18 years ago will no longer have to worry about compensation for their families when they’re gone,” Sen. Chuck Schumer said Tuesday.

“These men and women — many of them sick, some of them gravely so — won’t have to return to Congress any more for the compensation they always should have been given.”

First responders, their families and Stewart gathered in the Senate gallery to watch the bill’s final passage.

“I’m just thinking about everybody that isn’t here that we lost along the way,” Stewart told The Post. “Guys that gave their last days on this Earth fighting to see this through.”