<p>The Tarim Basin, the largest inland arid basin in the world, is characterized by limited precipitation due to the blocking effect of surrounding mountain ranges. Glaciers in these mountains play a crucial role in regulating the region’s hydrological system. Significant spatial variability in glacier dynamics around the High Mountains Surrounding the Tarim Basin (HMTB) has been documented, with accelerated thinning in the north, moderate thinning in the west, and anomalous mass gain in the south before 2015. However, the temporal dynamics of glacier changes and regional contrasts in the HMTB remain poorly understood due to the scarcity of continuous and consistent observational data. This study investigates glacier changes in the HMTB during 2003–2023 using merged multi-mission satellite altimetry data (ICESat GLAH14, CryoSat-2 L2I, and ICESat-2 ATL06), processed with Seasonal-Trend decomposition based on Loess (STL) to extract long-term trends from seasonal signals. A comparison between 2003–2009 and 2018–2023 reveals a recent weakening of spatial heterogeneity, characterized by accelerated thinning in the southern and western HMTB (e.g., East Kunlun from −0.11 ± 0.04 m yr⁻¹ to −0.22 ± 0.02 m yr⁻¹; Pamir from −0.23 ± 0.05 m yr⁻¹ to −0.35 ± 0.02 m yr⁻¹), reduced elevation gains in “Karakoram Anomaly” regions (e.g., West Kunlun from +0.19 ± 0.02 m yr⁻¹ to +0.06 ± 0.01 m yr⁻¹), and decelerated thinning in the northern HMTB (e.g., East Tien Shan from −0.60 ± 0.06 m yr⁻¹ to −0.52 ± 0.03 m yr⁻¹). This decrease in spatial heterogeneity may drive by declining winter-spring snowfall and intensified summer warming in the south and west, coupled with a slowdown autumn warming and increased spring snowfall in the north. However, the coarse spatial resolution of CryoSat-2 limits the construction of a continuous glacier monitoring time series at finer grid scales, hindering further detailed analysis of small-scale dynamics. Despite these limitations, our study provides important baseline data for future glacier change predictions and water resource planning.</p>