Metallic clusters, ranging from 1 to 2 nm in size, have emerged as promising candidates for creating nanoelectronic devices at the single-cluster level. With the intermediate quantum properties between metals and semiconductors, these metallic clusters offer an alternative pathway to silicon-based electronics and organic molecules for miniaturized electronics with dimensions below 5 nm. Significant progress has been made in studies of single-cluster electronic devices. However, a clear guide for selecting, synthesizing, and fabricating functional single-cluster electronic devices is still required. This review article provides a comprehensive overview of single-cluster electronic devices, including the mechanisms of electron transport, the fabrication of devices, and the regulations of electron transport properties. Furthermore, we discuss the challenges and future directions for single-cluster electronic devices and their potential applications.