The military charity was chosen by the Order’s murdered brethren committee as the benefactor of a fundraising initiative permanently marking the sacrifice of 333 members killed during the Troubles.
In 2014, an appeal was launched by the committee through the sale of lapel badges to commission a stain glass window as a contemporary tribute to those who lost their lives.
The window forms the centrepiece of the lodge room located in the Museum of Orange Heritage in Belfast.
Chairman of the murdered brethren memorial committee, Robert Abernethy, said: “It is both a privilege and an honour for the committee to support such a worthwhile cause.
“It is both poignant and fitting the memorial fund for the murdered brethren window should benefit the Poppy Appeal. Many of our members bravely wore the uniform of the security forces; protecting the community, and lost their lives or were maimed in their courageous stand against terrorism.
“We owe a special debt of gratitude to those who gave their lives, to their families and those who still carry the burden of physical and mental injuries. We will always remember them.”
Lyn Palmer, Royal British Legion community fundraising manager, said: “The Poppy Appeal is very grateful for this generous donation, which will help to support the beneficiaries of the Royal British Legion.”