In this chapter, we review our research for dependable service composition for smart cities in both cyber and physical spaces. For the cyber space, given the active investigation on web services or web APIs, we intensively worked on the problem of service composition that explores the "best" combination of available services from different providers. The key point was efficient exploration of enormous combinations both in terms of functional consistency and QoS. For the physical space, we worked on compositions of physical services given the trend of Internetof-Things (IoT). This direction focuses on consistency of composition as different services make physical effects on multiple users and shared spaces. At the end of this chapter, we discuss the prospect after these past research studies.