The fast-paced global urbanization phenomena pose huge workload to the city managers, demanding smart solutions for creating sustainable, efficient and citizen-centric urban spaces. Answering to this clarion call, smart cities have swiftly come of age in their efforts to leverage cutting-edge technologies for smarter infrastructure and better public services leading to enhanced lifestyles. However, the very complexity and scalability characterizing the smart city systems call for resilient solutions towards data security, transparency and efficiency. It is at this juncture that blockchain technology, being both decentralized and immutable-transparent in nature, comes into play by addressing the envisaged challenges. This chapter examines the extent to which the challenges facing the smart cities in developing secure digital infrastructures and protecting the data of city operations from cyber-attack and unauthorized access can be resolved through blockchain technology. It explores the blockchain abilities to deliver trusted real-time transactions, support decentralized applications and improve citizen engagement through transparent governance. It then, based on the same, brings out challenges toward regulatory, operational, and technical integration of blockchain into urban systems and emphasizes the need that these barriers must be surmounted to use this technology to its full potential in advancing smart cities. The chapter finally presents and discusses several case studies on the effective application of blockchain within the ecosystem of current smart cities concerning practical benefits and potential.