The energy company is to establish 500 projects in deprived areas that will be run by a network of local authorities, housing associations and charities.
Staff from each project will go into homes and deliver a free energy audit as well as determining whether each family can benefit from being put in touch with voluntary organisations.
Around four million of the country's poorest people spend more than 10 per cent of their income on keeping warm. It is an issue that impacts upon the work of charities involved in the project, namely Help the Aged, Scope, RNIB, Save the Children and the Family Welfare Association.
Scope's head of fundraising Aneesha Moreira said: "The majority of disabled people in Britain do live in poverty, so it makes sense for us to get involved in something like this.
"One of our aims is to reach the most disadvantaged people and this will help us achieve that."
The three-year project, which begins this autumn, represents a ?xA3;150 million investment. British Gas is putting in ?xA3;74 million and matched funding from local authorities accounts for the majority of the remainder.
Customer research carried out convinced British Gas it should focus its community relations initiatives on the most vulnerable.
Managing director Mark Clare said: "Our new alliance brings together the expertise of the charity sector as well as local authorities to build on our experience of tackling fuel poverty in the most constructive and long-lasting way.
"In the 21st century, it is a scandal that there are people dying due to cold-related illnesses and suffering as a result of the lack of essentials for life,
How much each charity will receive is yet to be revealed but the scheme is a significant milestone on the trend towards the voluntary sector becoming increasingly involved in service delivery.
Kim Darton, head of corporate development at Save the Children, said the campaign would tie in with the organisation's Beat Poverty campaign.
"We will be directly tackling child poverty in the UK by working with children in the UK to develop practical initiatives that challenge social exclusion,