The England wide ban follows the introduction of similar legislation in Wales, and both the driver and the smoker can be fined £50 if found flouting the law.
Experts say second hand smoke is particularly harmful to children and young people as they breathe more rapidly and have less developed airways. The problem is exacerbated in confined spaces, such as in the car or home.
A recent survey revealed that ending smoking in cars with children is supported by 85% of adults from the West Midlands.
Councillor Sandra Samuels, the City of Wolverhampton Council's Cabinet Member for Public Health and Wellbeing, said: "I welcome this ban on smoking in cars carrying children and young people; it is a significant victory in protecting them from the effects of second hand smoke.
"The British Lung Foundation estimates that more than 430,000 children are exposed to second hand smoke in cars each week, and passive smoking puts them at risk of serious conditions including respiratory infections, meningitis and asthma.
"Smokers should heed this new legislation, and also note the fact that the risk posed to children by smoking in cars in the same as it is smoking in the house. They should therefore consider the warning this ban sends out when they are thinking of lighting up at home.
"The good news is that there is plenty of help and support available to parents or guardians who wish to help smoking, and I would encourage them to contact Wolverhampton's Stop Smoking Service for more details."
While smoking rates have declined in recent years, it remains the biggest cause of preventable illness and premature death in the country - accounting for almost 80,000 deaths in England every year. One in every 2 long term smokers will die prematurely from a smoking related disease unless they quit.
For help and advice to quit smoking, please contact Wolverhampton Stop Smoking Service, which offers on to one support in GP practices, pharmacies and drop in clinics, a specialist pregnancy service and home visits, on 0800 073 4242 or 01902 444246.
Alternatively visit Type=links;Linkid=5080;Title=Smokefree NHS;Target=_blank; for a range of free support and quitting advice, and to sign up to Stoptober, the national 28 day quit campaign which also begins today.
- released: Thursday 1 October, 2015