Referrals to council children's services reached 646,120 last year, according to new figures from the Local Government Association (LGA).
The figures also showed more than 500 child protection investigations were started on average each day in 2016/17, increasing from 200 a decade ago.
The LGA said the figures highlighted the 'urgent' need for the Government to address the £2bn funding gap for children's services.
Chair of the LGA’s children and young people board, Cllr Richard Watts, said: 'With councils now having a child referred to them every 49 seconds on a daily basis, it is vital that they have the resources necessary to provide an effective response.
'The Government has been warned repeatedly that ongoing funding cuts, including the £2bn gap that councils face by 2020, have left them struggling to provide the support that vulnerable children and families need.'
Responding to the figures, head of local government at trade union Unison, Heather Wakefield, said: 'Children can't be protected from abuse on the cheap.
'The Government must give councils the cash they need to recruit more child protection staff and keep all children safe.'
Head of policy at charity Action for Children, Eleanor Briggs, added: 'Central government cuts to children’s services budgets have been nothing short of devastating and services that could intervene early to stop problems escalating have been among the hardest hit.
'With no long-term funding solution on the table, many children’s services are having to move towards a crisis firefighting approach.
'We’re calling on the Government to prioritise the services children need before this turns into a catastrophe for the next generation of children and families.'
And head of local government at auditors Grant Thornton, Paul Dossett, added: 'Children’s services have faced challenging savings targets over a number of years but, as these sobering figures show, demand has continued to rise.
'Due to continued funding reductions, 73% of all councils overspent on their budget for children’s social care services in 2015/16 to try and meet this rising need.
'It is essential more funding is made available to allow local authorities to intervene successfully before problems escalate and ensure families and vulnerable children are given the support they need.'