Official figures released by the Office for National Statistics (ONS) show that in 2018/19 4.2 million children were in families living in poverty - up from 4.1 million the previous year.
There are 600,000 more children living in poverty now than in 2010, figures show.
This means 30 per cent of children in the UK are living in families earning less than 60 per cent of the average household income after housing costs have been paid.
The figures show that 72 per cent of these children are from families where either one or both parents are working - up from 70 per cent in 2017/18.
Children’s charities have warned the UK is heading towards a child poverty crisis that is set to escalate due to the coronavirus pandemic.
According to the Department for Work and Pensions, over the past week around 500,000 people have applied for unemployment benefit through universal credit after losing their jobs as a result of factories, shops and businesses closing.
Director of policy and campaigns at Action for Children, Imran Hussain, said: “These grim figures show millions of families with children are already struggling to keep their heads above water even before they - and millions of others living comfortably – find themselves hit hard by the economic wave of this once-in-a-generation health crisis.
“In the past week some families have already got so desperate, our frontline staff are feeding them from their own cupboards. And with so many families close to breaking point, we’ve had to launch an appeal fund to help those struggling to pay for basic essentials like food, nappies and utility bills.
“We welcome the financial support announced last week but the government needs to go further and faster. We urgently need to put a protective shield around children in low-income families.”
Sam Royston, director of policy and research at the Children’s Society branded the figure “appalling”.
“This country is one of the richest in the world and we are letting future generations down by failing to end child poverty in the UK.
“The current coronavirus crisis is likely to see this number continue to rise as parents face job losses and falls in earnings.
“We welcome the coming together of politicians, professionals and communities to do everything it takes to respond to this crisis – including to address the additional pressure it will place on struggling families. The measures are a step in the right direction, however, faced by the levels of child poverty already present across the UK, and shown by these figures, much more needs to be done to protect families in coming days, weeks and months,” Royston said.
Earlier this week, Action for Children launched an emergency appeal amid fears that vulnerable families will struggle to stay afloat during the coronavirus outbreak.
Research by the charity found that 86 per cent of frontline workers were already speaking to parents worried about having enough money to stay afloat during the pandemic.