Abstract: The magnetospheric substorms play a crucial role in the dynamic processes of the Earth’s outer radiation belt. However, the specific influence of substorm evolution on the outer radiation belt remains insufficiently understood. This study investigates the effects of different substorm events on the outer radiation belt—specifically focusing on the enhancements of the source electrons (or chorus waves) and seed populations—by using joint observations from the THEMIS satellites and Van Allen Probes. Our analysis reveals the following key findings: (1) The magnetic field dipolarization in the near-Earth tail, triggered by the substorm expansion phase, is a key process that facilitates the earthward injections of energetic electrons and ultimately affects the dynamics of the outer radiation belt. (2) The activity level of chorus waves in the outer radiation belt is significantly modulated by the characteristics of substorm injected electrons and shows a certain event dependence. (3) The temporal structure of substorms (pulsed or continuous) will significantly affect the response patterns of the outer radiation belt (single response or multi-stage response). These findings provide valuable insights for advancing our understanding of the dynamic processes of the outer radiation belt.