<p>Circuit quantum electrodynamics (circuit QED) offers a promising platform for quantum information processing and quantum simulation. The quantum spatial searches for identifying a target vertex on a graph have broad applications across information technologies. However, implementing quantum spatial searches on a graph through circuit QED remains unexplored. In this paper, we propose a scheme to realize quantum spatial searches via continuous-time quantum walks in a circuit QED system. Here, each cavity represents a graph vertex, while a single superconducting (SC) qubit mediates interactions among all cavities, enabling coherent manipulation of the search process in complete graphs. Remarkably, we find that an increasing number of vertices leads to a shorter search time, and the search is achieved deterministically. Our numerical simulations for the target search in an eight-vertex complete graph agree well with theoretical predictions, even under realistic decoherence and experimental parameters. This protocol is universal and can be generalized to accomplish the same task in a wide range of physical systems, where multiple microwave or optical cavities couple to a single matter qubit of various types.</p>