© Clive Gee/PAUnder the proposal, the government will now have powers to introduce a new offence of exposing children to smoke in vehicles.
Smoking in cars carrying children is set to be banned after MPs overwhelmingly backed the plan in a free vote.
The House of Commons supported the plan, first put forward by Labour, despite the misgivings of some cabinet members, including Nick Clegg, over whether it will be too difficult to police.
Under the proposal the government will now have powers to introduce a new offence of exposing children to smoke in vehicles, with breaches of the law likely to incur a small fine.
David Cameron, who missed the vote, gave his personal backing to the idea, despite the government saying last week there was no need for the legislation.
"While he understands the concerns that some have expressed, his view is that the time for this kind of approach has come," the prime minister's spokesman said.
The shadow public health minister, Luciana Berger, who campaigned on the issue, said it was a "great victory for child health which will benefit hundreds of thousands of young people".
She added: "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.
Comment: Maybe soon they'll also be forced to ban nicotine gum, lest one of those pesky molecules escape the chewer's mouth and cause disastrous cancer in nearby innocent bystanders. In the mean time, educate yourself: 'World No Tobacco Day'? Let's All Light Up!