Hundreds of thousands of children could be saved from being exposed to second-hand smoke in cars after MPs paved the way for legislation which could see an end to the practice.
Leading medical charities have said they are "delighted" that MPs voted in favour of outlawing smoking in vehicles carrying children.
The Commons have given the health secretary the power to impose a ban despite the opposition of some MPs, including 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 are not tied to a party line.
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.
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 while Justice Secretary Chris Grayling was in the "no" camp of those who said it is unenforceable.
Deputy Prime Minister Nick Clegg has spoken out against attempts to "sub-contract responsible parenting to the state" and pro-smoking groups have branded it an "unnecessary intrusion".
Shadow public health minister Luciana Berger welcomed the result but warned ministers not to "kick this into the long grass".
She said : "This is a great victory for child health which will benefit hundreds of thousands of young people across our country. It is a matter of child protection, not adult choice.
"The will of Parliament has been clearly expressed today and this must be respected. Ministers now have a duty to bring forward regulations so that we can make this measure a reality and put protections for children in place as soon as possible.
"A time-limited consultation may be necessary on the practical details of implementation, but we will be watching closely to ensure the Government don't try and kick this into the long grass."