Cobalt (Co) is essential for clean energy development, but its extraction and processing have significant environmental and human health costs. We conducted an innovative assessment of the global environmental impacts of cobalt mining and the human health risks associated with mining and processing. We discovered that mining increased deforestation in tropical countries, particularly in South America and Africa with the affected areas of 309.41 and 134.11 km2. Oceania faced a considerable threat to biodiversity due to having the largest proportions (36.58%) and the largest mining area (409.55 km2) within protected areas. The protected area in northern South America (It index = 1316.93) had the highest level of biodiversity threat. The impact of mining on landscape integrity declined with increasing distance from mining areas in Asia, Europe, and North America. Meta-analysis highlighted the serious health risks from cobalt exposure, with miners (urine effect size 3.31) and metal workers (hair and nail effect sizes 5.76 and 5.60) showing significantly elevated Co levels. Children and women were particularly vulnerable to cobalt exposure. Our study quantified the forest loss, biodiversity threat, and landscape disturbance of cobalt mining and the health risks of Co exposure, underpinning the rebound in environmental fragility amid an energy transition.