Almost a quarter of three to six-year-olds use handsets and by the age of 15 almost every child has their own mobile.
However, experts warn there may be long-term health risks from exposure to emissions.
Children are thought to be most at risk because their thinner skulls make them more likely to absorb radiation from the phones.
In a survey of 1,000 parents the website moneysupermarket.com found more than 13% of parents with three-year-olds said their child had used a mobile phone. Among three to six-year-olds, the figure was 23%.
Scientists admit long-term mobile phone use could have serious health risks.
A £9million study published in September found no evidence of a link between short-term use and brain cancer, but experts behind the research said it was too early to know the health consequences of using a handset for more than a decade.
The Mobile Telecommunications and Health Research Programme did not tackle this issue and it may be years before the results of a separate £6million study into the effects on children are known.