Methane is a potent greenhouse gas with a global warming potential nearly thirty times greater than carbon dioxide. Rising emissions from agriculture, energy, and waste sectors threaten climate stability, food security, and public health. This review aims to evaluate methane sources, impacts, and mitigation strategies within the One Health framework, emphasizing measurable outcomes across human, animal, and environmental domains. A narrative synthesis was conducted using peer‑reviewed literature, climate reports, and policy briefs published between 2010 and 2025. The search strategy targeted methane emissions, mitigation technologies, and One Health applications. Case studies were prioritized to illustrate practical interventions. Evidence was organized thematically into sources, impacts, mitigation strategies, and governance frameworks, ensuring integration of scientific, operational, and policy perspectives. Methane emissions intensify atmospheric warming and act as precursors to tropospheric ozone, damaging crops, reducing carbon sequestration, and exacerbating respiratory illnesses. Mitigation strategies include dietary manipulation, feed additives, plant bio‑actives, probiotics, vaccines, selective breeding, and microbiome engineering. Case studies demonstrate measurable benefits: seaweed supplementation reduced cattle methane by up to 80%, alternate wetting and drying halved rice methane, and landfill gas capture lowered emissions while reducing vector‑borne disease risks. Methane reduction offers a unique opportunity to advance climate action, safeguard animal welfare, improve public health, and strengthen ecosystem resilience. Integrating scientific innovation, sustainable agricultural practices, collaborative governance within One Health provides a robust pathway for achieving global sustainability goals. Addressing methane as both a climate forcer and health determinant highlights its central role in cross‑sectoral mitigation strategies.