This chapter aims to analyses the blockchain technology in developing sustainable smart cities and tackling the challenges of urban development and improving the operation of the cities. It highlights how blockchain is potentially influencing the future development of such cities by addressing issues related to sustainable development and city management. In applying blockchain to smart cities, the technology improves the level of trust and openness necessary for public acceptance and joint activities in developing new approaches to urban life. The more details on the categories of understanding in explaining what blockchain is by using distributed ledger technology, cryptography, and consensus mechanisms, which are the basic building blocks of any blockchain system. A classification between public, private, and consortium blockchains is done with examples that outline how it is suitable for a certain application in an urban environment. It also explores how government security and transparency, management of wastes, transport options, as well as energy trading and management, can benefit from blockchain. Blockchain technology is an efficient and cost-effective solution when it comes to improving the work in cities, as well as the engagement of the citizens. The existing and potential research issues and possible future work, including scalability, compatibility of the different types of blockchain, and concerns about the right regulation that brings about the right ethical and secure use. Through these challenges, it would be possible to better inform future designs of smart city infrastructures. However, the use of blockchain technology is one of the efficient tools for the sustainable development of cities.