Julie Bentley, Action for Children's chief executive, accused the government of being "asleep on the job" for the past decade when it comes to investing in children.
"The next Prime Minister must wake up to this growing crisis and put our children first," she said. "We want to see the establishment of a National Childhood Strategy, so departments right across government can get a grip on these issues, backed with funding to deliver urgently needed services to keep children safe from harm."
The Choose Childhood: building a brighter future for our children report, released to coincide with the campaign launch, noted that in the past decade significant cuts to benefits and public services have combined to damage vulnerable children's life chances. This, it said, is leaving some children without support to face abuse and neglect, domestic violence, poverty and hunger.
To address this, a strategy is needed, which should be underpinned by investment in high quality, evidence-based prevention and early help for families from all four nations.
It also called on policymakers to better incentivise local agencies to provide help early and "end the cycle of increasing spend on crisis services". This includes continuing to invest in growing the evidence base and to sharing good practice around early help.
"The country is sleepwalking into a crisis in childhood and, far from being carefree, our children are buckling under the weight of unprecedented social pressures, global turmoil and a void in government policy which should keep them well and safe," Bentley said.
She added that Action for Children research shows that vulnerable children they work with are facing traumas like domestic abuse or neglect, going hungry or struggling with their mental health "without the support they desperately need".
Donna Molloy, director of policy and practice at the Early Intervention Foundation, backed Action for Children's call for a national strategy and increased investment.
"We know that many popular and widespread approaches to early intervention and early help have not been evaluated," she said. "This doesn't mean that they aren't effective, but it does mean we don't know - and as a country we cannot afford to spend valuable resources on forms of support that haven't been shown to improve outcomes for children and young people."
Molloy also agreed with the importance of using incentives to encourage long-term decisions about services and commissioning.
"It is vital to understand that the long-term pay-offs from effective early intervention will accrue to the whole of society and the wider economy, not just to the agencies or services making commissioning decisions today."
In response, Education Secretary Damian Hinds recognised the pressures and worries young people can feel, but said the government is "equipping young people for adulthood in a changing world, by identifying mental health problems and providing support in schools, encouraging young people to gain resilience and skills, and teaching [them] how to navigate the online world safely and constructively".
He added that the government is giving a voice to young people on issues they care about through a new Youth Charter that is being developed.