Smart cities represent a promising paradigm aimed at enhancing citizens’ quality of life through cutting-edge infrastructure and technological advancements. Collaborative services serve as a cornerstone for any smart city, fostering seamless cooperation among diverse entities, including government agencies, businesses, and individuals, thereby enhancing community outcomes. These services are pivotal, promoting seamless communication and collaboration among various smart applications, and facilitating data exchange, resource sharing, and functional interactions within smart city environments to optimize efficiency, effectiveness, and user experiences. However, the development and deployment of secure, interoperable services in smart cities present significant challenges. These issues encompass, ensuring data security compliance during interoperation, effective management of interconnected services, securely handling sensitive data across services, and addressing issues related to confidentiality, integrity, and availability (CIA) traits. To tackle these challenges, this research proposes an innovative adaptive security governance framework tailored for smart cities. This framework relies on dynamic security policies implemented through smart contracts to guarantee data security and privacy during smart service interoperation. Real-world use cases in collaborative smart city environments validate the framework, integrating multi-chain blockchain technology, smart services APIs, and Software-Defined Networking (SDN), showcasing its ability to enhance security and efficiency in collaborative services. This study contributes to the development of safe and efficient collaborative services inside smart cities, tackling administrative issues while emphasizing data security and privacy. Smart cities may improve citizens’ living conditions while successfully addressing crucial security problems in an ever-changing environment by using this architecture.