The rapid escalation of environmental degradation and ecosystem collapse has intensified global demand for sustainable energy alternatives. This paper examines the critical role of renewable energy systems — including solar, wind, hydropower, geothermal, and biomass — in mitigating environmental destruction and safeguarding natural ecosystems. Fossil fuel combustion remains the dominant driver of greenhouse gas emissions, air and water pollution, habitat fragmentation, and biodiversity loss. Transitioning toward renewable energy infrastructure offers a transformative pathway to significantly reduce carbon footprints, restore ecological balance, and minimize land-use conflicts associated with conventional energy extraction. The study analyzes comparative environmental impacts across energy technologies, evaluates policy frameworks promoting clean energy adoption, and investigates case studies where renewable integration has demonstrably reversed ecosystem degradation. Furthermore, the paper addresses existing challenges such as land occupation, wildlife interference, and resource consumption in renewable manufacturing. Findings suggest that strategically planned and responsibly deployed renewable energy systems not only curb atmospheric carbon concentration but also contribute to soil conservation, water quality preservation, and biodiversity protection. The paper concludes that a globally coordinated renewable energy transition, supported by robust environmental governance, is essential for achieving long-term ecological sustainability and climate resilience.