Doping can significantly affect the optical absorption characteristics and electrical properties of Ga₂O₃ via bandgap modulation, thus improving the performance of photodetectors. This study uses plasma-enhanced chemical vapor deposition (PECVD) to fabricate In-doped Ga₂O₃ films and investigates the influence mechanism and application potential of In doping on the performance of β-Ga₂O₃-based solar-blind photodetectors. This photodetector demonstrates remarkable deep-ultraviolet (DUV) response properties, reaching a photocurrent level of microamperes under 5 V bias and 275 μW/cm² illumination at a wavelength of 254 nm. Additionally, it achieves a maximum responsivity of 480 mA/W, a detectivity of 6.42×10¹³ Jones, an external quantum efficiency of 235%, a photoconductive gain of 2.15, and a maximum photo-to-dark current ratio of approximately 1×10⁶, thus demonstrating the extremely high sensitivity of In-doped Ga₂O₃ to low DUV light intensities and establishing its significant potential in optical sensing applications. High-temperature growth facilitates In doping; therefore, the photocurrent of In-doped β-Ga₂O₃ films is significantly higher than that of their counterparts without In doping under identical illumination and bias conditions. The presence of oxygen vacancies and lattice defects in the films significantly affects the performance of the photodetector, with surface oxygen vacancies affecting electron accumulation and migration through the adsorption of oxygen molecules and the formation of surface barriers. Consequently, the photocurrent response is enhanced under 254 nm ultraviolet light, whereas the optical-response parameters diminish as the light intensity increases, which is primarily due to the scattering and recombination of charge carriers. This study provides a comprehensive discussion on the fabrication methods and photoelectronic characteristics of In-doped Ga₂O₃ films. Our findings offer new insights into the design of high-efficiency In-doped Ga₂O₃ DUV photodetectors and provide new avenues for the application of PECVD technology in semiconductor materials.