According to statistics published on Thursday by the Government, the number of children classed as living in relative poverty is 2.3 million, the lowest level since the 1980s.
There had been speculation that the figure would increase to 2.5 million, while a row has been brewing over whether the Government is planning to change the way the figure is measured.
The current definition of child poverty is whether a child lives in a household with an income less than 60 per cent of the national average.
"It is a scandal that there are 200,000 more children who have been pushed deeper into poverty over the past year, as today's figures reveal," said Matthew Reed, Chief Executive of The Children's Society.
"There has also been a steady rise over the last five years in the numbers of children living in in-work poverty, clearly showing that even those families with jobs are suffering because of government policies.
"Moving the goal posts by changing the definition of child poverty will do nothing to help the millions of children who are suffering in real poverty.
"It is unacceptable that in this day and age, in one of the world's richest countries that 3.7 million children remain in poverty. Clearly the Government has failed to move closer to ending child poverty," added Mr Reed.
In his initial statement to MPs, Work and Pensions Secretary Iain Duncan Smith said he criticised the way child poverty is measured for a number of years.
But on Thursday he told the Commons: "I believe today's figures demonstrate that if you deal with the root causes of poverty - and I believe this Government is doing that - then even under a measure of poverty I have consistently over the last few years described as flawed, you can still have an impact."
He added: "Our fundamental belief is the most powerful way to change lives is to create a welfare system that makes work pay, writes no one off and supports people in to work."
Labour said the statistics show a "depressing slowdown" in the progress the UK should be making towards the abolition of child poverty in the UK.
