In this paper, a CMOS monolithic calibrated position-sensitive detector (PSD) for detecting light-spot position applications is newly proposed. A calibration technique is proposed in this work. With the calibration circuits, the proposed chip successfully detects the position of a small light in a real environment. Before performing the proposed calibration circuits, the maximum linear error is 54.55%. After calibration, the maximum linear error can be reduced to 3%. The light dynamic range of a light spot is 40 dB. The chip area is 2.87 × 2.72 mm<sup>2</sup>. The proposed chip is suitable for devices of measuring light-spot position.