Campaigners have expressed dismay at figures which show nearly a quarter of four and five-year-olds are obese.
The Department of Health statistics also reveal 31.6% of 10 to 11-year-olds are seriously overweight.
The data comes after around 80% of youngsters in the age ranges were weighed and measured as part of a Government scheme to fight obesity.
Stuart Barber, head of policy and public affairs at the British Heart Foundation, said: "These distressing figures confirm that a whole new generation of children are paying the price for decades of inaction.
"But it's not too late to reverse the trend.
"Young children are particularly susceptible to junk food advertising, which continually urges them to put their hearts and long-term health at risk."
Public health minister Dawn Primarolo said: "Whilst these figures come as no surprise, it is encouraging that 80% of children in years one and six have been weighed and measured.
"So far over 900,000 children have been weighed and measured as part of this programme.
"Knowing how many children are overweight or obese and spotting trends is key to ensuring that families, communities, public services, industry and Government take the right action in tackling obesity."