<p>Most Ga₂O₃-based heterojunction solar-blind ultraviolet (UV) photodetectors are typically manufactured using p-type semiconductors like SiC and GaN to form p-n junctions. However, their cutoff edges, corresponding to band gaps below 4.4 eV, fall outside the solar-blind UV range (200–280 nm), which leads to unwanted photo response and compromises their effectiveness in applications requiring high precision, such as military missile early warning systems. In this study, we address this issue by utilizing amorphous Ga₂O₃ and high Mg-doped MgZnO films to construct a metal–semiconductor-metal photodetector, featuring dual n–n junctions connected back-to-back. Using type II band alignment between the materials minimizes unwanted photo response, ensuring high solar-blind selectivity. Our photodetector achieves a responsivity of 13 mA W⁻¹, a detectivity of 5.85 × 10¹¹ Jones, a photo-to-dark current ratio of 672, and rise/decay times of 0.17 s/0.06 s under a bias of 5 V for 254 nm UV light. These performance metrics, combined with the device's stability under varying external bias voltages, demonstrate the potential of Ga₂O₃/MgZnO heterostructures for next-generation solar-blind UV photodetection, offering advancements in military-grade photonics applications and other fields requiring high precision.</p>