Fields in Trust, which was formerly known as the National Playing Fields Association, was set up by King George V in 1925.
The aim was to ensure all people young or old, able or disabled, should have access to free, local, outdoor space for sport, play or recreation.
The group's flagship policy is called Fields in Trust which sets out to protect as many outdoor recreation spaces as possible as a celebration of the Queen's Diamond Jubilee, the London Olympics and the Commonwealth Games.
City council officers nominated 28 sites that they suggested should be covered by the legal agreement.
These cover large areas like the Botanic Gardens, Cathkin Braes and Glasgow Green.
But there are also smaller areas of green including Naseby Park, Garnethill Peoples Park and Binghams Pond.
Alistair Watson the city council's sustainability and the environment spokesman, said: "By nominating a number of parks, the council is showing its commitment to promoting active lifestyles through the protection of our green space.
"This is yet another opportunity to build on the magnificent legacy of the Glasgow 2014 Commonwealth Games.
"The signing of this agreement is great news for Glaswegians.
"Essentially, this is a real badge of honour for these parks," he added.