Camila Batmanghelidjh has blamed "ill-spirited ministers" for forcing the Kids Company charity to close and "abandon a lot of children".
Ms Batmanghelidjh insisted she had acted "responsibly" and blasted the Government for "airbrushing" the circumstances surrounding the demise of the charity which she founded 19 years ago.
Kids Company will formally close its doors at 7pm, Ms Batmanghelidjh confirmed in a BBC Radio 4 interview.
In an interview due to broadcast in full at 8pm on Thursday, she said: "By the time you broadcast, unfortunately the charity's closed and we've had to abandon a lot of children."
She added: "That's it, it's the end of Kids Company and actually a bunch of rumour-mongering civil servants, ill-spirited ministers and the media, on the back of a range of rumours, put the nail in this organisation and shut it."
Ms Batmanghelidjh questioned David Cameron's role in the demise of her charity.
She said: "I have to think what do I do? There is insolvency law that requires you to behave in a particular way. Therefore, the doors have to shut and there cannot be any service provision - insurance stops, everything stops.
"But I am still left with these kids and their needs. This is devastating - where is the Prime Minister of this country saying what's going to happen to these children?"
Asked if she felt personal responsibility, Ms Batmanghelidjh said the charity had needed money for staff and running costs at a time when donors wanted to buy specific items, such as equipment. This meant Government funding was needed, she said.
"I can't run an organisation on the back of this level of uncertainty," she said.
"So the answer as far as I know I acted responsibly, I asked for help early enough and I feel that Government failed to honour its responsibility to these most vulnerable children.
"We live in a climate where everything is airbrushed by this Government."
The organisation works with 36,000 children and young people, and officials, charities and councils have been in discussions preparing for the impact the closure could have.
The youth organisation has been hit by allegations of bad financial management, prompting its high profile founder to quit as chief executive.
Ministers agreed to give the extra cash to help restructure the charity despite official objections from a Whitehall mandarin who warned they did not think it would offer "value for money".
Esther Keller, director of services for Kids Company in Bristol, said she felt anger at Westminster and concern for the children who would lose out on support.
She said staff were told this morning that the charity would close within 24 hours, with the doors set to be locked for the final time at 5pm.
She said: "I feel terrible sadness for the children and young people we have been working with for the past three years in Bristol. They will be hungry, they will be desperate because no therapists will be helping with their emotional state. It's going to be devastating."
The high-profile charity, which operates in London, Bristol and Liverpool, has been shaken by claims it has not properly managed its finances.
It received a £3 million grant from the Cabinet Office last week after agreeing, on the orders of the Government, to make changes in its leadership, management and governance.
But Ms Batmanghelidjh emailed staff within the charity last week to say they would be paid using some of the grant money, according to the BBC.
The BBC reported that the Cabinet Office is making plans to claw back the grant because it believes conditions attached to the use of the money were not met.
In a sign of official concerns about the funding for the charity, a senior Whitehall official took the rare step of requiring a written, direct order from ministers before agreeing to the latest lifeline for Kids Company amid concerns about how it would be spent.
In their reply, Cabinet Office Ministers Oliver Letwin, the Chancellor of the Duchy of Lancaster, and Matthew Hancock said they are "very mindful of the inspirational work that Kids Company does" and decided to release the funding anyway.
Acting Labour leader Harriet Harman, whose constituency of Camberwell and Peckham is served by Kids Company, demanded a plan to ensure the vulnerable youngsters the charity works with are cared for.
She said: "Whatever happens to Kids Company, these children and young people must be protected and supported. Such vulnerable young people must not suffer as a result of the breakdown of Government confidence in Kids Company."
Southwark Council, in south London, where many young people work with the charity, said: "Although Southwark doesn't refer any children to the charity, some will have sought out their services. We are ready to support any vulnerable children and young people in the borough who are affected by the closure of Kids Company."
A spokesman for Lambeth Council said: "We are aware of the concerns over the future of Kids Company and its work in Lambeth, and our priority is looking after the children and young people who rely on its services."