British members of parliament voted overwhelmingly on Monday in support of a ban on smoking in cars carrying children.
Lawmakers in the House of Commons, the lower house of parliament, voted in favour of a ban by 376 to 107.
It is now up to Prime Minister David Cameron's government to decide whether to actually bring a ban into effect.
Opponents of the measure had argued that legislation on the issue was not needed, and infringed people's freedoms.
Australia, Canada, South Africa and the United States already ban smoking in cars in which children are passengers.
Lawmakers were voting on an amendment to a bill, brought by the opposition Labour party, which gives the government the power to make it a criminal offence for drivers to fail to prevent smoking in their cars, although it does not mean the government necessarily has to.
The Conservative-Liberal Democrat coalition government gave lawmakers a free vote, meaning that they could decide on principle instead of being forced to toe the party line.
Cameron himself missed the vote because he was touring flood-hit areas in southwest England, but his spokesman said the prime minister believed "the time had come" for a ban.
A 2012 study carried out in Britain found that smoking in cars raises levels of dangerous fine-particle pollutants to many times the limit recommended by the world's health agency.