The European badger (Meles meles), a widespread and adaptable mustelid native to Europe and parts of Asia, has emerged as a valuable sentinel species for monitoring environmental health. This review compiles multidisciplinary evidence demonstrating the utility of badgers as bioindicators for environmental contamination, antimicrobial resistance (AMR), and zoonotic diseases. Their omnivorous diet, frequent soil contact, and proximity to human-modified landscapes facilitate exposure to a range of ecological stressors. This review summarizes studies across Europe from 2003 to 2022 have detected numerous contaminants in badger tissues—including heavy metals (e.g., cadmium, lead, mercury), trace elements, and persistent organic pollutants—highlighting localised environmental pollution. Badgers have also been shown to harbour antibiotic-resistant bacteria such as Escherichia coli, Staphylococcus aureus, and Enterococcus spp., often carrying resistance genes like SHV-12, vanA, and tet(B), suggesting their role in tracking environmental AMR spread. Additionally, badgers serve as reservoirs or incidental hosts for various zoonotic pathogens, including Mycobacterium bovis, Leptospira interrogans, Toxoplasma gondii, and Borrelia burgdorferi. The synthesis of this evidence supports the use of M. meles in One Health frameworks as a practical tool for assessing ecological risks and guiding public health and conservation strategies.