The new organisation will be called Constructing Excellence in the Built Environment.
Its aim will be to act as a facilitator between clients, industry and the government, and to be a provider of practical support to the construction industry.
The move has been welcomed by construction minister Nigel Griffiths, who said he believes the merger will give the organisation greater influence with the government. He said: 'I'm very enthusiastic about Constructing Excellence and Be coming together.
'It gives a powerful voice for the improvement agenda and creates one of the largest construction business networks in the UK,' he added.
Speaking on behalf of Be's existing membership, BDP director Richard Saxon said: 'Be's mission has always focused on improving the quality of the built environment and increasing value for clients and end users through collaboration.
'I am confident that, following this merger, Constructing Excellence in the Built Environment will be able to draw on the experience and knowledge of our members to continue the drive towards a world-class, sustainable industry,' Saxon added.