The law states that it will be an offence to smoke in a private vehicle with someone under age 18 in the car, and to fail to prevent smoking under the same circumstances.
The legislation applies to enclosed, private vehicles but not to anyone driving alone.
"Three million children are exposed to second-hand smoke in cars, putting their health at risk," the Public Health Minister Jane Ellis said.
"We know that many of them feel embarrassed or frightened to ask adults to stop smoking, which is why the regulations are an important step in protecting children from the harms of second-hand smoke."
The British Lung Foundation
said more than 80% of second-hand smoke contains cancer-causing toxins, which are more concentrated in the confines of a car.
Children are more susceptible to the harmful effects because their lungs are smaller, they breathe faster and have less developed immune systems.
Wales introduced a similar ban last year and the law is in addition to the prohibition of smoking in workplaces and enclosed public places, which was enforced in England in July 2007.
The ban also exists in a number of jurisdictions in Canada
, the United States and Australia, while other countries are considering the move.
South Africa and Bahrain do not allow smoking in cars with children present and Mauritius has banned smoking in all cars carrying any passenger.
The British Heart Foundation
welcomes the regulation as well as future plans to discourage young smokers.
"Parliament will shortly vote on introducing standardised packaging -- a key measure in helping to stop children from smoking," said Chief Executive Simon Gillespie.
"By ridding cigarette products of their distinctive designs we'll reduce the appeal of this uniquely lethal product damaging the heart health of future generations."
Mixed views are being expressed on Twitter.