A light-assisted biochemical sensor based on a light addressable potentiometric sensor is disclosed. The light-assisted biochemical sensor comprises a semiconductor substrate and a sensing layer, which are used to detect the specific ion concentration or the biological substance concentration of a detected solution. Lighting elements fabricated directly on the back surface of the semiconductor substrate directly illuminate the light to the semiconductor substrate, so as to enhance the photoconduction property of the semiconductor substrate. And then, the hysteresis and the sensing sensitivity of the light-assisted biochemical sensor are respectively reduced and improved. In addition, due to its characteristics of integration, the light-assisted biochemical sensor not only reduces the fabrication cost but also has portable properties and real-time detectable properties. As a result, its detection range and the application range are wider.