In the era of rapid digital transformation, the proliferation of data has become a defining feature of modern societies. The exponential growth of data generated from diverse sources such as sensors, mobile devices, social media, and digital transactions has led to the emergence of Big Data as a critical technological paradigm. This vast pool of data presents significant opportunities for innovation, particularly in the development of smart cities. Smart cities leverage Information and Communication Technologies (ICT) integrated with Big Data analytics to improve urban infrastructure, optimize resource utilization, and enhance the quality of life for citizens. This research paper provides a comprehensive analysis of the role of Big Data in smart city ecosystems. It explores key applications across sectors including healthcare, education, transportation, energy, and governance. Furthermore, the study examines the benefits, challenges, and future prospects of Big Data in urban development. The findings indicate that while Big Data has immense potential to transform urban living, challenges related to data security, privacy, integration, and governance must be addressed. The paper concludes by emphasizing the need for advanced analytical frameworks, policy interventions, and collaborative efforts to ensure sustainable smart city development