The construction giant will create nine new woodlands in partnership with the Blenheim Estate in Oxfordshire during the 25-year programme.
Chief Executive John Morgan said: “This exciting project is about more than our quest to achieve net zero – though that remains our very valid goal.
“This is about creating a legacy with an environmental net gain and the creation of substantial natural capital, across the board.
“Our woodlands will provide measurable, demonstrable gains in terms of soil, air and water quality, not to mention the wellbeing benefits for all those who can come and enjoy the forest as it grows.”
Blenheim Estates Director Roy Cox added: “This partnership with Morgan Sindall is a first for us and is incredibly exciting in terms of both scale and what it will deliver in improving our estate, the environment and surrounding communities.”
Morgan Sindall declined to confirm the cost of the scheme but said it would be a “substantial sum”.
The contractor will help fund, design and create the woodlands in collaboration with Cotswolds-based forestry company Nicholsons.
The woods will incorporate 28 carefully selected varieties of trees – including Hornbeam, Lime, Sycamore, Wild Cherry, Oak, Norway Maple, Alder and Beech.