Ministers are making it a legal duty for the government, local authorities and other organisations to help to end child poverty across the UK.
The government looks set to miss its own targets on cutting the numbers of children living in poverty.
A new bill being published later will make it a duty to support families so that child poverty is eradicated by 2020, the goal set by Tony Blair.
Campaigners say this means future governments cannot easily drop the aim.
The latest figures available, for 2007/8, put the number of children living in poverty at 2.9 million.
Poverty in this case is measured relatively - those who live in households with an income of less than 60% of the average.
Since Tony Blair set the target of ending child poverty by 2020, the government says it has lifted half a million children out of poverty, down from 3.4 million in 1999.
The then prime minister also set a target to halve the numbers of children in poverty by 2010 - but that looks unlikely to be met.
Ministers say measures taken since the 2007 Budget will move another 500,000 children out of poverty, but that will still leave 2.4 million in that position.
Under the Child Poverty Bill, a legal duty to work together to support families to end child poverty will be placed on central government, councils and services including the police, NHS primary care trusts and youth offending agencies.
It requires the Westminster government to publish a UK-wide child poverty strategy, which must be revised every three years.
It also puts the same duty on Scottish and Northern Irish ministers.
It sets out four targets to be met by 2020 across the UK, which the government says will "define the eradication of poverty".
These include having fewer than 10% of children living in relative low income poverty (i.e. in households with less than 60% of average).
The bill will also establish a child poverty commission to advise on strategies to tackle child poverty.
The main ways the government tries to move children's families out of poverty include changes to the tax and benefits system, including tax credits, and a wider approach to raising skills and closing the education achievement gap between rich and poor.
Providing better housing and children's centres such as Sure Start are also part of the drive.
Work and Pensions Secretary Yvette Cooper said the government was planning to invest £5bn in unemployment relief in an effort to reduce child poverty.
"This bill is about giving every child a fair chance in life.
"I want a society where children don't miss out on school trips, aren't stuck in poor housing with no space to do their homework and aren't left behind because they don't have a computer or internet access.
"This is a big challenge, and one which we will not shy away from. It holds current and future government's feet to the flames and won't allow any government to quietly forget about child poverty or walk away."
But Conservative spokeswoman for work and pensions Theresa May said the pledge to halve child poverty by 2010 was "just one of countless Labour promises that lays in tatters".
"It is a tragedy that the number of children falling into the poverty cycle is continuing to rise," she said.
"The government needs to wake up and get a grip of this problem. Simply relying on means-tested benefits to address the symptoms of poverty is unsustainable. Instead we must tackle the root causes of poverty, such as educational failure, family breakdown, drug abuse, indebtedness and crime."
The Child Poverty Action Group said the new bill was a "major step in the fight to end Britain's child poverty shame".
The group's chief executive, Kate Green said: "You rarely see such high levels of child poverty as we have in the UK in other wealthy countries and that is clearly wrong.
"We must stop so many of our children growing up with worse health, poor life chances and a lower life expectancy.
"The bill will mean action on child poverty is no longer optional for future governments, it will be mandatory."