The mass migration of rural citizens toward urban areas in search of better employment opportunities, better education erupts a new threat for urban citizens. The increased population due to migration contributes in increasing traffic jams, green house gas emissions, waste disposal. To provide better day‐to‐day services to citizens, common issues such as fair broadband distribution and connectivity, digital and knowledge inclusion needs to be respected with possible integration and smooth management of various social, physical, and business infrastructure. Furthermore, the rapid development of digital society opens up vast of opportunities in smart cities thus implementing goals of education and healthcare for all, green society, green city. However, the continued adoption of new technologies such as internet of things (IoT) and cloud technologies for various applications in smart cities suffers from issues such as high latency, bandwidth bottlenecks, scalability, security, and privacy. The smart cities are usually autonomous in nature, which relies on distributed infrastructure and features applications such as intelligent information processing, heterogeneous network infrastructure, ubiquitous sensing, and intelligent control systems implemented in areas such as public safety, healthcare, and diagnosis. Besides, the blockchain‐enabled applications such as data platform for sharing valuable data between non‐trusted organizations, blockchain‐based financial systems, online games, online education system, and identity management system improve reliability and democratization of cities by eliminating centralization. However, majority of applications depends on either digital signature or public key cryptography‐based schemes which, in turn, depend on the premise that computation of private key from public key is computationally hard. But with advent of quantum computer, the time complexity of all hard problems such as discrete log problem and integer factorization has reduced from millions of years to few seconds, thus endangering traditional cryptographic mechanism, which includes public key, secret key, and digital signature–based protocols used in blockchain technology–based services in smart cities. The quantum computing which uses law of physics for communication does not depend on mathematically hard problems. In addition, convergence of quantum computing with blockchain technology provides us with amicable solutions for smart cities. This chapter discusses overview of quantum computing, key characteristics, and quantum key distribution and presents an architecture enabling post‐quantum blockchain–based applications within smart cities. In addition, the need of various services relying on quantum blockchain in smart cities is presented. Moreover, to enable conceptual architecture for post‐quantum blockchain– enabled services in smart cities, smart contracts are designed for implementing transportation application.