It was gazetted in 1996 and covers 5,193 km2 (2,005 sq mi), ranging from the Buller River near Murchison in the south, to the base of Farewell Spit in Golden Bay in the north.

[3] The area had an abundance of food resources, with middens from a site near the mouth of the Whakapoāi (Heaphy River) showing evidence of local Māori hunting bush moa, kekeno, and kurī.

[4]: 30–31  Excavation of the same site also demonstrated connections to trade routes running throughout New Zealand, with pounamu from the Arahura region and obsidian from Mayor Island / Tūhua in the Bay of Plenty both being used in the area.

One particular example is the Gouland Downs, an area with unusual geology and vegetation, situated at around 600 m (2,000 ft) elevation to the west of Mt Perry.

The Forest Service started on a programme of work to promote recreation in the park, including cutting new tracks and building huts.

[5][15][16] Although the area does not have the iconic geographic features of previously established New Zealand national parks, at the time of its creation there was increasing interest in protecting biodiversity and geodiversity.

In his announcement about the establishment of the park, the Minister of Conservation, Denis Marshall said: "It consists of extensive areas of native forest and limestone and marble landscape which has international significance".

[18] For the official opening, a ministerial party led by the prime minister, Jim Bolger, Denis Marshall, and Nick Smith (MP for the Tasman electorate) was flown by helicopter to Balloon Hut, south of the Cobb Reservoir.

[19][20] Five small parcels consisting of unmodified coastal areas and forest with high conservation values totalling 900 ha (2,200 acres) were added to the park in 2016.

[21] In 2007, Kahurangi National Park was added to the tentative list of UNESCO World Heritage Sites, along with Farewell Spit and the Canaan karst system.

[26] The significance of the Mokihinui region to the Ngāi Tahu iwi and Ngāti Waewae, the rūnanga for the area, was marked with the placement of a pouwhenua in July 2019.

Rocky reefs and seastacks provide a habitat for encrusting animals, invertebrates and inshore fish that thrive in murky waters.

Beneath the tussock in the Gouland Downs are sandstone and mudstone sedimentary rocks that were formed in the Lower Palaeozoic era around 400 to 500 million years ago.

The land was subsequently uplifted, and erosion removed most of the limestone, leaving isolated outcrops that now appear like tree-covered islands in the tussock landscape.

[44] The Honeycomb Hill Cave area in the basin was discovered in 1976, and in 1982 was given the status of a site of global significance in paleozoology due to discoveries of bones of several species that had become extinct.

In prevailing westerly conditions, moisture-laden air from the Tasman Sea is forced to rise over the high elevations of the western ranges.

[51] The Aorere River and its tributaries have a catchment area of 573 km2 (221 sq mi) draining the Haupiri and Wakamarama ranges in the north of the park.

[58] The Euphrates Cave skull supports "the hypothesis that takahē were widespread across the South Island's subalpine habitats and lowland areas at the time of human arrival in New Zealand".

The high level of endemism has arisen as a result of complex biogeographic processes, and indicates that during the Pleistocene ice ages, the area was an important refuge.

[4]: 26 The complex geology and landforms have allowed unique plant communities to develop in localised environments, leading to a high rate of endemism.

Other native birds that can be found in the park include pipit, kererū, the New Zealand falcon, weka, robin, fantail, bellbird, grey warbler, tūī, tomtit, rifleman, fernbird and brown creeper.

In addition to the whio, freshwater birds that are found in wetlands and waterways in the park include the Australasian bittern (classified as vulnerable), and the New Zealand scaup.

[109] As of 2024, the society has approximately 68 km (42 mi) of trap lines to control stoats, protecting around 5,000 ha (12,000 acres) of beech forest and tussockland habitat.

The society is focussed on the recovery of whio (blue duck) in the Flora Stream catchment, and the re-introduction of Great spotted kiwi.

[116] Conservation initiatives for whio (blue duck) in the park have resulted in a large increase in their numbers since 1998–2000 when surveys of the population were first conducted.

The majority of the track is in river valleys and under forest cover, with small sections in tussock land at Stag Flat and the Little Wanganui Saddle.

The trailheads are the Lyell Historic Reserve on State Highway 6 in the Upper Buller Gorge, and the Rough and Tumble Bush Lodge, located 4 km (2.5 mi) from Seddonville, northwest of Westport on the West Coast.

In 2019, 64,400 ha (159,000 acres) of conservation stewardship land in the Mōkihinui River catchment was added to Kahurangi National Park, including much of the route of the Old Ghost Road trail.

[126] In 2014, a link was found between the Nettlebed and Stormy Pot caves in the Mount Arthur region of the park, creating a system that was around 10 km (6.2 mi) long and 1,200 m (3,900 ft) deep, and the deepest in New Zealand.

[4]: 123 Kahurangi National Park is the setting for a young adult novel Night Tribe, written by Peter Butler, a Nelson-based entrepreneur and author.