Ecosystem services (ES) are essential to human well-being. Assessing dynamics of ES is crucial to shaping the concept of sustainable development and creating public understanding of the status of ES. This study proposes to quantify the change in ES value in response to Land cover/land use (LCLU) changes over the past 33 years in the Rift Valley Lakes Region of Ethiopia. A combined approach of LCLU classification and modified ES value coefficients was employed for quantifying the ES value. Results revealed that approximately USD196.04 ×10 6 (12.4%) of ES value was lost during the study period. Although cropland experienced a dramatic expansion, the total gain in ES value of the cropland was too small to balance out the overall loss. A continuous reduction in values of specific ES functions has also occurred except for food production, biological control, and pollination service function over the last three decades, indicating an apparent deterioration of the fragile Rift Valley ecosystem. Hence, to enhance the continuous supply of ES and economic development, an integrated approach to managing land and water resources is recommended. Moreover, payment for ES is also a potential remedy for ES loss at the regional and local scale.