The present study assesses the spatio-temporal dynamics of land use/cover over a 28-year period in the upper Tana River Basin (TRB), Kenya using digital change detection techniques. The results indicate that during the last three decades, agricultural land and built-up area have increased by 32.57% (184,796 ha) and 26.35% (1460 ha) respectively, while open land, waterbodies and vegetation have decreased by 35.9%, 3.13% and 8.29% respectively. There was a huge expansion of agricultural land to marginal semi-arid and arid areas (lower part of the basin) over the period. The results of this study provide a better understanding of the spatial and temporal dynamics of the natural resources and form a basis for better planning and effective spatial organization. Such information can help various stakeholders including policy decision-makers in balancing development needs and river basin vital environmental systems protection and sustainability, especially in arid and semi-arid regions.