The deal is set to create a business with around 750 financial and mortgage advisers.
Kevin McDonagh, chief executive of On-Line Partnership Group, said the firm would continue to operate both network brands separately for the foreseeable future.
Ian Mclver, managing director of The Whitechurch Network, said: “After some initial discussions, On-Line Partnership Group found that our business and our own work in preparing for the retail distribution review made us an extremely attractive fit with their other network.
“We are excited at the prospect of becoming part of this larger group and being able to deliver an even better level of service to our members.”
