This paper presents the fabrication and characterization of ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as \( G \approx 10^6 \). The photoconduction mechanism is elucidated through time-resolved measurements spanning a wide temporal domain, revealing the coexistence of fast (τ ~ 20 ns) and slow (τ ~ 10 s) components of carrier relaxation dynamics. The high photoconductive gain is attributed to oxygen-related hole-trap states at the NW surface, which prevent charge-carrier recombination and extend the photocarrier lifetime. This mechanism is effective even at the shortest time scale investigated (t < 1 ns). Despite the slow relaxation time, the high internal gain results in gain-bandwidth products (GB) exceeding ~10 GHz. The high gain and low power consumption of NW photodetectors make them promising for applications such as sensing, imaging, and intrachip optical interconnects. The study also highlights the unique properties of NWs for photosensing applications and enables the design of novel photodetector architectures.This paper presents the fabrication and characterization of ZnO nanowire (NW) visible-blind UV photodetectors with internal photoconductive gain as high as \( G \approx 10^6 \). The photoconduction mechanism is elucidated through time-resolved measurements spanning a wide temporal domain, revealing the coexistence of fast (τ ~ 20 ns) and slow (τ ~ 10 s) components of carrier relaxation dynamics. The high photoconductive gain is attributed to oxygen-related hole-trap states at the NW surface, which prevent charge-carrier recombination and extend the photocarrier lifetime. This mechanism is effective even at the shortest time scale investigated (t < 1 ns). Despite the slow relaxation time, the high internal gain results in gain-bandwidth products (GB) exceeding ~10 GHz. The high gain and low power consumption of NW photodetectors make them promising for applications such as sensing, imaging, and intrachip optical interconnects. The study also highlights the unique properties of NWs for photosensing applications and enables the design of novel photodetector architectures.