Mount Elgon National Park is a national park 140 kilometers northeast of Lake Victoria. The park covers an area of 1,279 square kilometers and is bisected by the border of Kenya and Uganda. The Ugandan part of the park covers 1,110 km2 while the Kenyan part covers 169 km2. The Kenyan part of the park was gazetted in 1968, the Ugandan part in 1992.

Elgon’s slopes support a rich variety of vegetation ranging from montane forest to high open moorland studded with the giant lobelia, groundsel and heather plants. The vegetation varies with altitude. The mountain slopes are covered with Elgon olive (Olea capensis subsp. macrocarpa) and Pouteria adolfi-friedericii wet montane forest. At higher altitudes, this changes to olive and Afrocarpus gracilior forest, and then an Afrocarpus and bamboo Arundinaria alpina zone. Higher still is a Hagenia abyssinica zone and then moorland with heaths Erica arborea and Erica trimera, tussock grasses such as Agrostis gracilifolia and Festuca pilgeri, herbs such as Alchemilla, Helichrysum, Lobelia, and the giant groundsels Senecio barbatipes and Senecio elgonensis.

The botanical diversity of the park includes giant Afrocarpus, Elgon olive (Olea capensis subsp. macrocarpa), African juniper (Juniperus procera), pillarwood (Cassipourea malosana), elderberry (Sambucus adnata), pure stands of Afrocarpus gracilior and many orchids.

Of the 400 species recorded for the area the following are of particular note as they only occur in high altitude broadleaf montane forest: Ardisiandra wettsteinii, Carduus afromontanus, Echinops hoehnelii, Ranunculus keniensis (previously thought to be endemic to Mount Kenya), and Romulea keniensis

The Uganda Protectorate administration gazetted its side of Mount Elgon a Forest Reserve, managed by the Forestry Department, in 1929. In 1937, the boundary survey was completed but parcels were repeatedly degazetted to provide land for local residents. In 1940, the area became the Mount Elgon Crown Forest and in 1951 a Central Forest Reserve.

In 1983, the Ugandan government opened up a 6,000-hectare (15,000-acre) of the reserve for settlement by the encroaching Benet-Ndorobo group. An additional 1,500 hectares (3,700 acres) were settled illegally. The area legally remained a part of the reserve until 2002 when it was officially degazetted. Management of the park disintegrated during the civil wars. In January 1994, the reserve was finally converted into a national park, although timber harvesting continued in some areas.

The park is named after Mount Elgon, an extinct shield volcano on the border of Uganda and Kenya.

Mount Elgon National Park is uniquely split down the middle by the Kenyan-Ugandan border. Mount Elgon is an important water catchment for the Nzoia River, which flows to Lake Victoria, and for the Turkwel River (known as the Suam River in Uganda), which flows into Lake Turkana.

The climate is moist to moderate dry. Annual rainfall is over 1,270 millimetres. The dry seasons run from June to August and from December to March, although it can rain at any time.