Due to a great variability in elevation, a rich diversity of climates, flora and fauna can be found within the park. Research has revealed that on the comparatively small area of the mountain there are 1,500 species of higher plants, 500 species of fungi, 500 species of algae, 326 species of mosses, and 200 species of lichens. Among the, 31 species are Balkan endemics and 52 species are included in the IUCN Red List of endangered species.

The forests are mainly composed of Norway spruce and Bulgarian fir, with some Macedonian pine, Scots pine, and at the tree-line, mountain pine, and mixed deciduous forest at lower altitudes, mainly beech, birch, aspen and alder. Regarding herbaceous plants, well-established populations of Veratrum album are present on the mountain, as well as other species commonly called ‘lilies’. There are also orchids, such as the East European green-winged orchid (Orchis morio) that grows in the higher parts. Lungwort (Pulmonaria officinalis) is another widespread herbaceous plant on Vitosha; it develops in dank sites under the shade of the forest.

At a time when nature conservation ideas were a long way from the present understanding, some enlightened noblemen took the first step in 1934 by declaring 66 km² of Vitosha a nature park, hence Vitosha became the first park of this kind in the Balkans. During the following year, some of the early Bulgarian reserves, Bistrishko Branishte (subsequently expanded to 10.61 km²) and Torfeno Branishte (7.84 km² respectively), were designated within its boundaries. The park boundaries fluctuated over many years and today it encompasses the entire mountain; an area of 266.06 km².

Since the ancient times of the Thracians a large population has always existed at the base of Vitosha. For the last four thousand years the economy of this large settlement has always been connected, in one way or another, with the neighboring mountain. The name Vitosha comes from the two-peaked, twin ridge mountain, which rises above the Sofia field and has acquired its present shape in stages over many millennia.