Rapid urbanization has become a defining global trend, with over half of the world’s population now residing in urban areas—a figure projected to rise to two-thirds by 2050. While cities occupy less than five percent of the Earth’s surface, they concentrate significant natural and human resources, making urban planning critical for sustainable development. The expansion of towns and cities drives infrastructural development and human activities that profoundly affect natural vegetation, landscape, and environmental quality. In many developing countries, urban growth is often unplanned or haphazard, resulting in extensive paved surfaces, buildings, and road networks that replace natural landscapes and exacerbate environmental pressures. This study examines the impacts of urban expansion on green spaces and environmental sustainability, with a focus on Lafia Town, Nasarawa State, Nigeria. Urbanization not only reduces access to natural environments but also increases exposure to environmental hazards, including heat stress, flooding, and air pollution. The replacement of vegetated areas with impervious surfaces amplifies these hazards by altering local microclimates, increasing surface runoff, and reducing ecological resilience. As cities face growing population pressures and limited resources, integrating urban green spaces into planning frameworks has become essential for mitigating environmental risks, enhancing livability, and promoting sustainable development. By analyzing the state of green space planning in Lafia, this study highlights the challenges and opportunities in promoting environmentally conscious urban development. The findings underscore the need for strategic planning that balances urban growth with ecological preservation, ensuring that future expansions contribute to climate resilience, social well-being, and sustainable urban livelihoods. This research provides actionable insights for policymakers, urban planners, and stakeholders, emphasizing that green space planning is not only a tool for environmental management but also a pathway toward achieving long-term urban sustainability.