Action for Children ran 120 centres last year but that figure has now slumped to 87.
These have been shut down or taken back in-house by councils as they look to tackle "reduced funding from central government", said the charity.
The charity stresses it is not behind the closures, with decisions around closures being taken by councils.
Its income from children's services has fallen by £4m, from £120m in 2017/18 to £116m in 2018/19 as a result, the organisation reports.
It has also seen its staffing levels drop by 6.5 per cent, from 4,931 in 2017/18 to 4,608 in 2018/19.
The figures have been published in the charity's latest annual report and accounts.
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This notes that total spending on children's centres nationally has "fallen sharply" from £1.5bn in 2010/11 to £579m in 2017/18 and more than 1,000 centres have closed since 2009.
"This means many young parents and families don't get the vital support they need," states the report.
The charity's board of trustees chair Sarika Patel also reiterates the financial constraints and mounting demand for support being faced by local authorities.
"Today, Action for Children is at a critical point," states Patel.
"Cuts to budgets have placed huge pressure on local authorities and children's services.
"This at a time when, every 15 minutes, a child is moved into care for their own safety."
Action for Children chief executive officer Julie Bentley's foreword to the report also flags up the funding problems councils are facing.
She states: "As a decade of austerity takes its toll, we're seeing a widening divide between rich and poor.
"There is a fully-fledged crisis in funding for children's services,and we're working in an increasingly competitive commissioning and fundraising environment.
"This, at a time, when more and more children need our help."
Children's centre cuts were also highlighted in Action for Children's annual accounts last year. This found that 128 centres it was running had either closed or had reduced services.
The charity had taken over the running of dozens of children's centres formerly run by 4Children, which went into administration in 2016.
In April this year, the government launched a review of children's centres which the Department for Education said will look at these and "other delivery models to find out what works well".
Ten East Sussex children's centres under threat
Ten children's centres are under threat in East Sussex, with the county council approving a reduction in the number of council run centres from 26 to 16.
The decision is part of a revised early help strategy to save £2.6m, reducing the budget to £4.4m.
The council reports it is in discussions over the running of the 10 centres, adding: "If alternative providers cannot be found, it is expected the centres will close in April 2020."
The council said its early years' service will operate from 16 children's centres and youth centres and help target support to more than 2,000 families and young people at the risk of needing social care intervention each year.
All families in East Sussex will continue to have access to the School Health Service, the Family Information Service and improved online advice and information about the services offered by the county council, while Health Visiting services will continue for pre-school children.
Additional services will be maintained where externally funded support is available and a further 200 families will be supported through the Troubled Family Programme.
As well as targeted support for families, the county council is continuing to discuss details of possible open access drop-in facilities with partners.