Abstract: This paper presents a systematic review of the research progress on aerospace radiation-hardened gallium nitride (GaN) power devices and their associated driving and application technologies. Firstly, the wide bandgap and high electron mobility characteristics of GaN materials are analyzed, along with their advantages in radiation-hardened, high-frequency switching. The importance of device process optimization (e.g., FinFET structure and vertical device design) and packaging technology for performance improvement is highlighted. Secondly, the mechanisms by which aerospace radiation environments (protons, neutrons, and gamma rays) affect the electrical properties of GaN devices (e.g., threshold voltage shift and single-event burnout) are explored in depth, and multi-level radiation hardening strategies (e.g., material selection, dual-gate structure, and circuit-level shielding) are summarized. Further application examples of GaN devices in aerospace power systems, such as isolated DC-DC converters (peak efficiency reaching 94%) and resonant converters, are reviewed, highlighting their potential for improving power density and reliability. Finally, challenges such as compound radiation synergy, high-frequency thermal management, and driver circuit robustness are identified, and the direction of miniaturization, cost-effectiveness, intelligence, and high power are envisioned.