The Turgen-Aksuu Glacier, located in the Chon-Ashuu river basin in Kyrgyzstan, is a critical water resource for the region. Field observations conducted between 2018 and 2024, in collaboration with the Finnish Meteorological Institute and the Kyrgyz Hydromet Service, provided important data on the glacier’s mass balance, snow accumulation, and area changes, including UAV-based mapping. The glacier’s area in 2024 was measured at 5.13 km², a 19% decrease from its size in 1965 (6.3 km²). To analyze changes in glacier mass balance, we used DMBSim, a physical glacier surface mass balance model that simulates glacier mass balance using meteorological and topographic data. The model can be calibrated with mass balance measurements and provides detailed time series and mass balance maps. The mass balance of Turgen-Aksuu Glacier shows significant negative trends, with the glacier losing 1.1 m w.e. between 2023 and 2024 and more than 17 m w.e. since 1970, indicating continued degradation. In 2024, the accumulation zone covered 31% of the glacier’s total area, and the average annual mass loss was about 1.2 m w.e./year. The ongoing retreat and negative mass balance of Turgen-Aksuu Glacier highlight the impact of climate change on glacier health, with significant implications for the region’s water resources. Continued monitoring and further modeling are essential to understand the future dynamics of the glacier and to inform water management strategies.