St Leonard's Forest is at the western end of the Wealden Forest Ridge which runs from Horsham to Tonbridge, and is part of the High Weald Area of Outstanding Natural Beauty. It lies on the ridge to the south of the A264 between Horsham and Crawley with the villages of Colgate and Lower Beeding within it. The A24 lies to west and A23 to the East and A272 through Cowfold to the south. Much has been cleared, but a large area is still wooded. Forestry England has 289 ha. (714 acres) which is open to the public (many regard this as The St. Leonard's Forest), as are Owlbeech (mainly heathland) and Leechpool Woods (claimed by Horsham District Council to be ancient woodland) to the east of Horsham, and Buchan Country Park to the SW of Crawley. The rest is private with just a few public footpaths and bridleways. Leonardslee Gardens were open to the public until July 2010 and re-opened in April 2019. An area of 85.4 hectares (211 acres) is St Leonards Forest Site of Special Scientific Interest.The main car parks are at Roosthole close to Mannings Heath Golf Club for the Forestry Commission, Owlbeech/Leechpool on Harwood Road (B2195), and Buchan Country Park on the A264.
The High Weald Landscape Trail leads from Horsham Station east across the forest to Handcross. The Sussex Ouse Valley Way crosses the south of the forest from Lower Beeding to Handcross.
It is one of the "Fower stately Wood Nymphs" (Michael Drayton, 1611, Poly-Olbion, Song 17) of the Forest Ridge (the other three being Worth, Ashdown and Waterdown forests) which were part of the ancient Andreaswald or Andreadswald, now the Weald.
Earlier used for hunting, by the 16th century they were the centre of the English iron industry. The hammer ponds remain, the dams of those in St. Leonard's forest being crossed by Hammerpond Road between Horsham and Handcross, and today are used for fishing.