The accelerated retreat of glaciers on the Tibetan Plateau has led to the mobilization and downstream transport of accumulated heavy metals, posing a potential risk to downstream ecosystems and human health. However, current research on the distribution and ecological risk of heavy metals in glacier retreat areas remains limited. This study targeted the monsoon temperate Midui Glacier in southeastern Xizang China and investigated the distribution and ecological risk of typical heavy metals in its debris and soils in the retreat and water environments. The results showed that soil heavy metal content range from 144.8 to 520.0 mg/kg, which was dominated by Zn, As, and Cr, with relatively large spatial variation. The Cd and Hg concentrations were low. Soil heavy metal levels progressively increased from the debris to different stages of the retreat area, driven by soil development, vegetation succession, and intensified human activities, with the highest content observed in the third retreat stage. Most heavy metals (except Cu, Pb, and Hg) exhibited significant differences among the retreat stages but were significantly correlated with soil pH and nutrients. In glacial meltwater, the concentrations of heavy metals from proglacial lakes to downstream rivers vary between 3.76 and 33.37 μg/L, and remain well below Class I water quality standards. Notably, elevated levels were detected near the outlet of the proglacial lake (Guangxie Cuo) from the Midui Glacier viewpoint, and downstream, passing through the village, reflecting the strong influence of anthropogenic activities. The ecological risk assessment revealed that heavy metals pose a moderate potential ecological risk in soils, which are dominated by Cd and As, whereas there is no risk in the water environment. These findings offer critical baseline data and a valuable case study for understanding heavy metal biogeochemistry under glacier ecosystem changes on the Tibetan Plateau.