Some groups are having funding withdrawn altogether, the study of councils across England by anti-cuts website False Economy showed.
The cuts have totalled over £10m in the past year but the final figure is likely to be far higher because some authorities have not yet finalised their plans, said the report.
Many of the charities facing cuts deal with disabled people, children, the elderly and adult care, said False Economy.
The group's campaign director, Clifford Singer, said: "These cuts go deep into the voluntary and community sectors.
In practice the Big Society is looking more and more like a big con.
Trades Union Congress (TUC) general secretary Brendan Barber
"These are not just nice-to-have groups but organisations [which provide] vital services for older people trying to maintain independent lives, vulnerable children and abused women."
Adventure playground KIDS, based in Hackney in east London, offers services for children with disabilities and learning difficulties.
Organisers say councils are cutting back on funding the playground for vital services.
Alex Mills, national services manager for KIDS told Sky News: "There is no Plan B. If we don't get enough funding then we can't run services like this.
"We foresee that if local authorities look at only the short term by making small cuts here and there, then they aren't really looking at the long term, and the fact that they will have to invest thousands more pounds in the future to support these families who won't have this service right at the start.''
Simon Bierman takes his two sons to the playground most weeks and he is not convinced the group can survive on volunteers alone.
"The Big Society looks good on paper but the fact is that people have problems and pressures of their own," he said.
"Some of the kids here need professional help and that costs money."
Charity groups and trade unions are now rounding on David Cameron's Big Society idea, claiming that it is not working.
Trades Union Congress (TUC) general secretary Brendan Barber said: "These deep cuts to voluntary groups across the UK show that Government claims that charities can replace direct services currently provided by central or local government are false.
"It sounds great, but in practice the Big Society is looking more and more like a big con."
A spokesman for the Department for Communities and Local Government added: "The Government has provided a fair and progressive funding settlement for councils that protect frontline services and shield the most vulnerable.
"Councils have challenging decisions to make around how they prioritise spending but the Government is clear that councils must resist any temptation to pass on disproportionate savings to the voluntary sector."