The arrangement, which the charities are calling an 'amalgamation', sees Life Education become a majority-owned subsidiary of Coram and adopt the name Coram Life Education.
But Life Education, which uses a fleet of mobile classrooms to give children health messages on subjects such as drugs and healthy eating, has retained independent charitable status.
Coram has taken a 75 per cent stake in Life Education, and Life Education's 38 local groups have the remaining 25 per cent. Life Education's trustees will still however control the constitution and mission of the organisation.
Stephen Burgess, national director of Coram Life Education, said: "We think it's unusual in the most positive way and quite an innovative approach to ensuring that while we gain all the strength and depth of Coram as the UK's oldest charity, we retain the community engagement of Life Education that is so critical to our work."
The charities said the partnership would enhance their overall impact because while Coram worked with families and young people with social problems, Life Education had a preventative role.
Life Education employs 130 staff around the country and six in its head office and no redundancies will result from the arrangement. The charity has relocated its headquarters to the three-acre Coram community campus in Russell Square, London.