Disability United, a consortium comprising Leonard Cheshire, Action for Blind People, Mencap and the MS Society, will pitch for "major corporate donations" and split the proceeds four ways.
It marks a departure for charity fundraising strategy, which has traditionally seen fierce competition between organisations with similar aims, earning the sector the nickname the "shark-infested puddle".
Mark Bishop, head of corporate fundraising at Leonard Cheshire, said: "Disability United is unique. It's the first time that charities that are technically rivals have chosen to join forces. In the corporate sector, partnerships and alliances are encouraged - even feverishly pursued. It makes sense for the charitable sector to do the same."
According to the consortium, the attraction for corporate donors is that their donations will have more impact. "It gives a unique opportunity to businesses who can now support four charities with a single campaign," said Bishop.
Corporate representatives have welcomed the consortium. Fiona Rawes, director of Heart of the City, which encourages the charitable involvement of financial institutions in the City of London, said: "It's great to see several charities coming together to create their own fundraising consortium. Disability United offers companies the combined expertise and resources of four different organisations. Their shared case for funding is very compelling."
The idea for the consortium emerged from last year's European Year of the Disabled. Trials involving two large companies were successful, so the charities agreed for formalise the relationship. "We do not have any donations to date, although we are confident that Disability United will report some early successes in the not too distant future," said a spokesman for Leonard Cheshire.
Bishop denied the link-up had been prompted by difficulties in securing corporate donations, which provide just 4.3 per cent of the charity sector's income. "None of the four charities has entered into Disability United from a position of weakness - far from it. We simply believe that there is even greater strength in numbers."