Current land-use trends in Kenya's montane forest ecosystems show that land uses are changing fast due to natural and anthropogenic factors and these changes could have devastating effects on the environment. One such montane forest is the transboundary Mt. Elgon forest located in western Kenya. This study analysed trends in land use–land cover changes in Mt. Elgon forest ecosystem over the last 45 years. Landsat imageries downloaded from the United States Geological Survey archives were used to assess land use–land cover changes between 1973 and 2019 by applying supervised classification using Arc GIS 10.5. The IDRISI Selva 17.0 was used to calculate area under different land uses and generate change maps. The major Land Use–Land Cover (LULC) classified were mixed farming, natural forests, planted forests, bamboo forest, fallow land, tea plantation. The landsat images had an average overall classification accuracy of 87.12% and kappa coefficient (K) of 0.84. The kappa coefficient was rated as substantial and the classified images qualified for further analysis. Results established that there was an 18% decline in the natural forest cover between 1977 and 2019. There was a similar decline of 15.19% in bamboo forest cover. Plantation forests established in the 1990's also showed a 15.6% decline between 1999 and 2019. There was, however, a 29% increase in mixed farming, a 10% increase in fallow land and a 0.13% increase in tea plantations. These changes in land uses and land cover call for an urgent need to develop sustainable management plans to protect and conserve the Mt. Elgon forest ecosystem. Sustainable land management strategies to be used in the future may include education on the significance of the forest ecosystem, community participation in sustainable utilisation of forest eco-services and the introduction of sustainable alternative sources of livelihoods, such as bee farming.