APPC chair Paul Bristow hailed the merger vote as a historic night for the UK’s lobbying industry that will help elevate the voice of lobbying and provide much greater support to members.
"The APPC was formed in the wake of direct challenges and threats facing our industry," Bristow said.
"Almost a quarter of a century on our members face new, albeit different, threats from the growth of regulation. By merging with the PRCA we will can now offer our members a stronger and more united voice."
Bristow acknowledged the merger debate had stirred strong passions about the future of the self-regulator and has now called for unity from both sides.
He said the APPC’s Management Committee would meet early next week to begin the transition process.
Opposition to the merger has crystalised into the Campaign for an Independent APPC.
Campaign co-ordinators Emily Wallace and Darren Caplan congratulated the pro-merger faction and have reiterated calls for unity after what had been an at times fractious debate.
In a joint statement, they added: "Clearly this has been a tight race and it is important that the voice of those who supported the pro independence campaign is heard too, when the PRCA’s new ‘Public Affairs Board’ is set up.
"The plans proposed by the pro merger campaign now need to be consulted on properly and implemented with the support of the entire industry. As those plans are adopted we ask that the ‘Gold Standard’ Code of Conduct, lobbying register, training and complaints procedure is maintained.
"In particular, we would expect to see all members fully consulted about any proposed future changes to the Code."
PRCA director general Francis Ingham ‘loudly applauded’ APPC’s members decision to join forces.
He said: "By uniting our two organisations, we will create an incredibly powerful voice for our industry as a force for democratic good; and an even more powerful self regulatory body as we set and enforce the industry’s gold standard ethical code. This is a great day for lobbying."