In recent decades, the escalating frequency of environmental risk events, arising from sources such as industrial accidents, chemical spills, or other anthropogenic activities, has intensified threats to the ecological environment. The targeted identification of high-risk areas, formulation of control lists for key risk sources within regions, and the implementation of differentiated management strategies remain significant challenges. This study employs administrative region environmental risk assessment and gridded environmental risk analysis method to comprehensively evaluate environmental risks in the city of Kunming, China. The results indicated a fourfold increase in the number of environmental risk sources from 2012 to 2022. The sources were found to be widely distributed across the entire region but exhibiting localized clustering. Environmental risk receptors were primarily concentrated around a local lake, in densely populated counties, and near rivers and drinking water sources. Risk hotspot areas within the target region were identified using the gridded environmental risk analysis method. A list of 29 key control areas was proposed taking in 9 industrial parks and 20 streets. Measures were proposed for handling unexpected incidents. The findings provide data useful for policy formulation and environmental management in similar regions of mountainous cities.