Fields close to the Northamptonshire/Oxfordshire border are to become a "rich mosaic" of meadows, wetlands and woodland to help boost biodiversity.
The 85 acre (34 hectare) "habitat bank" at Greatworth, near Brackley, will support species including great crested newts, common toads, grass snakes, polecats, brown hares and water vole.
Managed by Environment Bank, it is part of a national scheme which allows developers to invest in land to meet a planning requirement to offset environmental harm.
"It'll be exciting to watch the site develop and the land improve over time," said Adam Crouch, who is overseeing the project.