There are now almost two million fewer smokers since the smoking ban was introduced in England 10 years ago, Cancer Research UK said.
As it celebrated the 10th anniversary of the law, the charity said smoking rates were now the lowest ever recorded - praising the ban as having one of the biggest impacts on public health of the last decade.
Laws people from lighting up in almost all enclosed public places in England came into effect on July 1, 2007 - following Wales, Scotland and Northern Ireland.
It covers places including offices, warehouses, factories, pubs, restaurants, railway stations, working vehicles and leisure centres.
Since then, the proportion of 16 to 24-year-olds who smoke fell from 26 per cent in 2007 to 17 per cent.
And a poll of more than 4,300 people for the charity found that just 12 per cent are in favour of repealing the ban.
Sir Harpal Kumar, Cancer Research UK's chief executive, said he was "thrilled" by the "enormous success" of the law - but urged the government to continue working on its Tobacco Control Plan.
Meanwhile, a report by campaign group Action on Smoking and Heath (Ash) said there was increasing public support for further restrictions on tobacco - even among smokers themselves.
Measures such as licensing schemes for tobacco sellers and a levy on the tobacco industry to pay for schemes to reduce smoking have been mooted.
But smokers' group Forest argued that the rise in e-cigarettes had had a greater impact.
Public Health Minister Steve Brine said the government would continue working towards make the next generation smoke-free.
"As a nation we can be extremely proud of the progress we have made on smoking rates, which are at their lowest ever levels. We truly are world leaders in this area, through our smoke-free legislation, plain packaging laws and ban on smoking in cars with children," he said.
"However, we know that smoking remains our biggest preventable killer and the job is by no means done. We will soon be releasing a new Tobacco Control Plan, to map our path toward a smoke-free generation."