Pudding Wood near Broomfield Hospital in Chelmsford, once overgrown and unloved, was turned into an attractive area for walks and festivals.
Trees were thinned and coppiced while undergrowth was cleared to ensure light reached the woodland floor and encouraged bluebells, butterflies and birds to flourish.
Forestry Commission helped fund the work, which included new paths, a footbridge, benches and the upkeep of glades.
Trees were planted into failing areas and white-owl, dove, robin, tit and bat boxes went up along with information boards. Leaflets rounded off the work.
Mid Essex Hospitals worked with the Forestry Commission and D.F. Clark Bionomique tree and landscape consultancy.
Contractors and volunteers were also helped by funds and wherewithal from Essex County Council and Chelmsford Borough Council.
Lindsey Allen, woodland officer of the Forestry Commission, said: "The woodlands had limited access with unclear paths and dangerous trees.
"The trees have been made safe and the paths are now defined and surfaced. Access is far better with walkways and extra light has made the woodlands more inviting."
Denise Mortimer, hospital trust project manager, said: "We wanted to improve the trust's carbon footprint and reverse the trend where parts of wood had been lost to new buildings.
"There is also evidence showing that woodlands help the healing process, and we will be pursuing this with various initiatives where patients can make use of the area."