At a meeting in Nottingham yesterday, 99 per cent of members who voted supported the move, which is expected to see all NFS business transferred to the Oddfellows on December 30.
The merger with Oddfellows will mean the closure of the NFS office in Nottingham and the loss of nine jobs.
The NFS board initiated merger talks last May when it decided that joining forces with a larger organisation would reduce costs and enhance the prospects of its members receiving significantly better investment returns.
Formed in 1812, the Nottingham Friendly Society has 10,000 members and around £13m under management in its with profits fund.
It also has 16,000 active CTF accounts totalling £7m.
The Oddfellows, also known as the Independent Order of Odd Fellows, Manchester Unity Friendly Society has over 90,000 members and over a quarter of a billion pounds in assets.
NFS chief executive Roger Leach says: “It is sad, but with modern regulatory constraints and compliance costs you need scale to deliver the returns your members expect.”
Oddfellows chief executive Philip Howcroft says: “I’m delighted at yesterday’s result and look forward to welcoming Nottingham Friendly Society members.
“We are both non-profit-making mutuals with a philosophy of putting our members at the forefront of our operations.”