Charity Bank has secured a £500,000 equity investment from Barclays.
The investment follows permission from the Charity Commission to create a new category of non-charity shareholder.
The Financial Services Authority has also given permission for the move, which takes Charity Bank's share capital to just below £4.5m.
Charity Bank's chief executive Malcolm Hayday said: "This investment provides a platform to launch our 2005 growth strategy by boosting our lending capacity."
Barclays will not earn dividends from its investment as these are only available to charity shareholders. But it will gain tax breaks under the Treasury's Community Investment Tax Relief scheme.
Barclays vice chairman and executive director Chris Lendrum commented: "Promoting financial inclusion is key to Barclays. We would urge other banks to follow our lead as this increases support for charities operating in some of our poorest communities."