We demonstrated an ultrahigh-performance and self-powered β-Ga2O3 thin film solar-blind photodetector fabricated on a cost-effective Si substrate using a high-temperature seed layer (HSL). The polycrystalline β-Ga2O3 thin film deposited with HSL shows high performance in the solar-blind region in comparison to the amorphous Ga2O3 thin film deposited without HSL. The zero-bias digitizing sensor prototype with an HSL produces a digitized output bit with deep UV (DUV) light that exhibits a high on/off (I254 nm/Idark) ratio of >103, a record-low dark current of 1.43 pA, and high stability and reproducibility over 100 cycles even after >2100 h. The photodetector shows minimum persistent photoconductivity and fast response in milliseconds. The photodetector yields a responsivity of 96.13 A W-1 with an external quantum efficiency of 4.76 × 104 at 5 V for 250 nm monochromatic light. The photodetector shows a high response to even a rare weak signal of DUV (44 nW/cm2). These values are the highest reported to date for a planar β-Ga2O3 thin film based photodetector despite the use of the cost-effective substrate. The asymmetric I-V curve indicates a dissimilar Schottky barrier height at the two ends of the MSM photodetector, which is discussed as the main reason for the high response even at zero bias. This work provides the guidelines to develop a β-Ga2O3-based cost-effective, self-powered, high-performance, and fast DUV photodetector that possesses a high potential for next-generation practical solar-blind photodetector application. © 2018 American Chemical Society.