Venturesome, the social lending arm of the Charities Aid Foundation, has attracted £3m of funding and given out more than £1m of loans through its Social Impact Fund, which it launched in June this year.
The fund allows philanthropists who hold CAF trust accounts to invest their charitable capital at no interest through Venturesome.
To start a CAF trust, a philanthropist must commit at least £10,000 for donation. CAF trust accounts contain a combined total of about £630m.
Paul Cheng, head of Venturesome, said the early popularity of the fund had exceeded expectations.
"We’ve had a lot of people commit their money to us for six years," he said. "We expect the amount of money we’ll have to lend will grow as awareness increases."
Cheng said there was also high demand for charities for working capital funding from Venturesome, and the demand was growing fast.