Derbyshire and Nottinghamshire Chamber of Commerce (DNCC) and its sister organisation in Leicestershire were merged during a signing ceremony last week.
DNCC President Tim Parker and James Bowie, his opposite number at the Leicestershire Chamber of Commerce, signed the merger agreement at East Midlands Airport on Wednesday.
The new Chamber will operate under a single group company, trading as DNCC in Derbyshire and Nottinghamshire and Leicestershire Chamber of Commerce in Leicestershire.
George Cowcher, chief executive of DNCC, will become group chief executive.
At 3,200, DNCC is currently the second largest Chamber of Commerce in the UK in terms of the number of businesses it has in membership.
Leicestershire’s membership stands at 750 and adding that to the DNCC roll will not change its position, but will take it a long way ahead of the UK’s third largest Chamber, which is the North East.
Mr Cowcher said: “The signing brings to an end a long process of negotiation and completes the merger. Member businesses from both Chambers recognise the value of merging.”