Brigid Heywood, Mike LeRoy, Chris Shaw, Tim Skelton, David Thompson and Helaine Whiteside will join a 21-strong Board, which steers the direction of the work of The Parks Trust.
The Trust cares for 4,500 acres of parkland across the city, including Campbell Park, Willen Lake and Linford Wood.
The Parks Trust chief executive David Foster said: "Milton Keynes' parks and green spaces are one of the city's greatest assets and the role of Trustee is a huge responsibility.
"Appointing new Trustees now will ease the succession of our existing Trustees retiring in the coming years.
"Each brings their own unique views and experience and will add their skills to the expertise of our existing board members."
Each Trustee is a volunteer board member and is appointed initially for a three year term.
Brigid Heywood is Pro-Vice-Chancellor (Research and Enterprise) at The Open University.
Mike LeRoy is a council member and Trustee of the British Entomological & Natural History Society and works at Westminster City Council as Environment Policy Manager.
Chris Shaw is a chartered surveyor and managing director of Countrywide Surveyors Ltd based in Stony Stratford.
Tim Skelton is a chartered surveyor and is head of estates for Domino's Pizza Group Ltd. He was formerly a property manager and senior surveyor with Milton Keynes Development Corporation.
David Thompson works for Natural England as a senior policy advisor and started his career as a seasonal ranger with The Parks Trust.
Helaine Whiteside is a property lawyer practicing in Milton Keynes.