The park boasts a spectacularly diverse landscape mosaic of diverse ecosystems and habitats, as well as the associated biodiversity. The area covers an area of 215,000 hectares in the heart of the Bale Arsi Massif in the southeastern Ethiopian Highlands, in Oromia State. Volcanic mountain ranges and peaks rise above the plateau, most notably Tullu Dimtu, Ethiopia's second-highest mountain at 4,377 m above sea level. It is easily explored by car, as all-weather roads provide access to most of its most attractive habitats. The all-weather road across the Sanetti Plateau to the 4,377 m peak of Tulu Dimtu is, in fact, the highest in Africa. Elsewhere in the park, extensive grasslands thrive alongside various forest types, including heath, bamboo, and juniper woodlands. Significantly, the southern slopes of the Bale Mountains drop dramatically into the famous Harenna Forest, Ethiopia's second-largest humid tropical forest, including patches of cloud forest. Due to its high elevation, Bale Mountain National Park boasts a high level of plant diversity, with approximately 1,321 species of flowering plants, 14% of which are native to Bale alone.

The Helichrysum (“everlasting”) flowers are the park’s most striking blooms, providing a beautiful yellow backdrop for the park’s incredible wildlife.

The park and its surroundings are home to exceptional flora and fauna, with an exceptionally high proportion of endemic species and, in some cases, the only remaining populations of globally threatened species from numerous taxonomic groups. For example, the Mountain Nyala and the Bale Monkey are endemic to this region and the country as a whole, as are numerous endemic rodents and amphibians, as well as the largest remaining population of the Ethiopian wolf. The southern part of the park is covered with wild forest coffee and medicinal plants such as Hagenia, which is used by local people to treat tapeworms.

The Bale Mountains are the best place in Ethiopia to observe the majestic and mysterious Ethiopian wolf. Unfortunately, this species is threatened with extinction due to the country's agricultural expansion; fewer than 400 individuals remain in the wild. It is the rarest canid in the world. The wolf is endemic to Ethiopia and is found nowhere else in the world.

The Mountain Nyala is an elusive and majestic antelope species found exclusively in the highlands of Ethiopia. It is characterized by its striking appearance: its robust body, slate-gray fur, and distinctive white stripes and spots, which blend seamlessly into the montane forests and scrubland in which it lives. These high-altitude areas, particularly the Bale Mountains and the Harenna Forest, provide the Mountain Nyala with an ideal habitat, where it thrives in the cool, misty climate. Despite its beauty and ecological importance, the mountain Nyala faces significant threats from habitat destruction, human encroachment, and poaching. The Mountain Nyala is a symbol of Ethiopia's rich biodiversity and a testament to the unique wildlife of the country's mountain regions. The Mountain Nyala is listed as vulnerable by the IUCN; no special hunting permits are required other than a valid license.

Harenna Forest is located in an upland forest area of the Bale Mountains in the Oromia Region of southeastern Ethiopia. This beautiful, jungle-like region is a biodiversity hotspot with a variety of native species. As one of the last remaining natural forests in the country, its rich flora and fauna supports a unique wildlife. Golden-crowned Bale monkeys, giant forest hogs, and a variety of colorful birds are often best observed in the enormous heath trees. Nyalas, various buck species, and even lions and panthers live in the forest.

Harenna Forest, south of Sanetti, supports the greatest diversity of large mammals in the park. These include the remarkable giant forest hog (the world's largest pig) and the highly localized Bale monkey, an endangered endemic species whose range is limited due to its specialized diet of bamboo.

Sanetti plateau: Bale is the world's most extensive Afroalpine fenland and consists of heather tussocks interspersed with icy alpine lakes and ethereal giant lobelia. The northern slopes below Sanetti are home to a mix of juniper-hagenia woodlands and Afromontane grasslands, while the southern slopes are covered in patches of heath, bamboo, and Afromontane forest. Bale's high-altitude centerpiece is an extensive lava plateau with several volcanic cones over 4,200 meters high.

Bale is considered the best place in Ethiopia for observing endemic birds. Six national endemics are represented here, along with eleven other species found only in Eritrea and several more that are unique to the Horn of Africa. The Juniper-Hagenia forest around Dinsho is home to forest species such as the Black-winged Lovebird, the White-cheeked Turaco, the Abyssinian Catbird, and the Yellow-fronted Parrot. In the higher elevations of Sanetti, the Spot-breasted Red-billed Warbler, the Alpine Chat, the Chestnut-naped Francolin, and the Eurasian Plover are among the species found. The incredible birdlife is reflected in the African Birding Club's ranking of Bale as one of the continent's top five bird-watching hotspots.