Rapid urbanization and industrialization have significantly transformed natural landscapes into densely built environments characterized by concrete structures, asphalt pavements, reduced vegetation, and increased anthropogenic heat generation. These changes have contributed to the development of the Urban Heat Island (UHI) effect, where urban areas experience significantly higher temperatures than surrounding rural regions. The Urban Heat Island effect negatively impacts environmental quality, public health, energy consumption, water resources, and urban sustainability. Increasing global temperatures and climate change further intensify UHI-related problems in modern cities. This article presents a comprehensive review of the Urban Heat Island effect and mitigation strategies, including causes, impacts, measurement techniques, environmental consequences, and sustainable urban planning approaches. The study examines factors such as land-use changes, transportation systems, building materials, energy consumption, and reduced vegetation contributing to urban heat accumulation. Various mitigation measures including green roofs, urban forestry, cool pavements, reflective materials, water-sensitive urban design, and smart city technologies are discussed in detail. Modern technologies such as Geographic Information Systems (GIS), remote sensing, artificial intelligence, and climate modeling used in UHI assessment and management are also analyzed. The findings indicate that integrated urban planning and sustainable mitigation strategies are essential for reducing urban heat stress, improving environmental quality, and enhancing climate resilience in urban areas