Campaigners have welcomed plans backed by MPs which could save h undreds of thousands of children from being exposed to second-hand smoke in cars.
Leading medical charities said they were "delighted" that Parliament voted in favour of paving the way for for legislation which could outlaw smoking in vehicles carrying children.
The Commons gave the Health Secretary the power to impose a ban despite the opposition of some MPs, including leading members of the Cabinet.
Ministers were granted a free vote on the measure - successfully introduced by Labour in a House of Lords amendment to the Children and Families Bill - meaning they were not tied to a party line.
The British Medical Association (BMA), which has campaigned for a ban since 2011, said the vote was an "important step forward in reducing tobacco harm".
Dr Penny Woods, chief executive of the British Lung Foundation, said: "Having campaigned on this issue for many years, we're absolutely delighted that MPs have backed the ban on smoking in cars carrying children.
"This could prove a great leap forward for the health of our nation's children.
"The introduction of a law that would help prevent hundreds of thousands of children from being exposed to second-hand smoke in the car is now within reach.
"With both Houses of Parliament having made their support for the ban clear, the onus is now on the Government to act accordingly and make this crucial child protection measure law at the earliest opportunity."
The charity estimates that in England more than 430,000 children aged 11 to 15 are exposed to second-hand smoke in cars every week.
Research published by the organisation last year concluded that 185,000 children of the same age are exposed to smoke while in the family car on "most days", if not every day.
Deborah Arnott, chief executive of health charity Ash (Action on Smoking and Health) described the vote as "an historic victory for Parliament and for children's health".
Tory and Liberal Democrat MPs joined forces with Labour MPs to approve the ban by 376 votes to 107, majority 269.
Prime Minister David Cameron missed the vote while visiting flood-stricken areas in the south west.
Mr Cameron's official spokesman declined to say which way the Prime Minister would have voted had he been able to attend Parliament.
But he told a regular Westminster media briefing: "While he understands the concerns that some have expressed, his view is that the time for this kind of approach has come."
Health Secretary Jeremy Hunt was in favour of the move, together with Chancellor George Osborne, Chief Secretary Danny Alexander, Defence Secretary Philip Hammond and Education Secretary Michael Gove, International Development Secretary Justine Greening, Scotland Secretary Alistair Carmichael and Energy Secretary Ed Davey.
Justice Secretary Chris Grayling was in the "no" camp of those who said it was unenforceable.
Home Secretary Theresa May, Work and Pensions Secretary Iain Duncan Smith and Northern Ireland Secretary Theresa Villiers also opposed the ban.
Deputy Prime Minister Nick Clegg missed the vote but has spoken out against attempts to "sub-contract responsible parenting to the state".
Also missing were Foreign Secretary William Hague, Business Secretary Vince Cable, Communities Secretary Eric Pickles, Environment Secretary Owen Paterson, who is out recovering from eye surgery, Transport Secretary Patrick McLoughlin, Culture Secretary Maria Miller and Wales Secretary David Jones.
Shadow public health minister Luciana Berger welcomed the result as a "great victory for child health" but warned ministers not to "kick this into the long grass".
But pro-smoking groups branded the move as an "unnecessary intrusion".
Simon Clark, director of the smokers' group Forest, said he was "disappointed but not surprised" by the decision and accused the Government of being "spineless".
He added: "Legislation will have very little impact because so few adults still smoke in cars carrying children. Those that do will carry on because it will be very difficult to enforce.
"Government has banned smoking in public places. Now they're going to ban it in a private place. The home will be next."
Health Minister Jane Ellison told MPs the success of a smoking ban in cars carrying children will not be measured by the number of times the police enforce it.
Instead, she said, its success would be gauged by the reduction in exposure to second-hand smoke.
AA president Edmund King said: "As has been the case with enforcing the ban on hand-held phones while driving, campaigns and legislation have been shown to reduce illegal behaviour afterwards. If a new law manages to make more adults think twice before lighting up with the kids on board, it will have helped."
A Department of Health spokesman said: "Second-hand smoke is harmful to children and it is right that this has been debated in Parliament. We will now determine how this amendment should be taken forward."