Ultraviolet (UV) photodetectors (PDs) are essential for a range of applications, such as space exploration, radiation monitoring, electronics manufacturing, etc. Zinc oxide (ZnO), a wide-bandgap n-type semiconductor, demonstrates high sensitivity to UV light, making it a promising material for UV PDs. This study investigates the impact of rare-earth (RE) doping–especially (lanthanum (La), neodymium (Nd), and dysprosium (Dy)–on the photodetection performance of ZnO based UV PDs. Hydrothermally synthesized RE: ZnO nanostructures were incorporated into fabricated RE: ZnO-Cu2O UV PDs, leading to significant performance enhancements. We present a detailed analysis of structural, morphological, and optoelectrical properties. Results show that RE incorporation transforms ZnO nanoparticles morphology into flake-like structures and increases charge carrier density (confirmed by Mott-Schottky measurements). These modifications yield enhanced photocurrent efficiency and charge carrier density, leading to superior photodetection capabilities. The RE-doped configuration also demonstrates improved response and decay times in UV photodetection studies. This study underscores the potential of RE doping to markedly enhance the performance of ZnO-based UV-PDs.