There is a great demand for the development of self-powered physical sensors for wearable applications in recent years. However, it is still challenging to achieve self-powered sensors with a high stability, accuracy, and linearity. Here, a novel wearable self-powered pressure sensor based on the integration of a piezo-transmittance microporous elastomer (PTME) and a thin-film organic solar cell (OSC) is proposed. In contrast to the sensors based on other mechanisms such as piezoelectricity or triboelectricity, the proposed self-powered pressure sensor is cable of measuring static pressure continuously and stably, and utilizes the ambient light as the power source regardless of its intensity. The PTME shows the light transmittance changes by a gradual closure of micropores with compression in response to the applied pressure. This unique optical characteristics of the PTME enables the OSC to generate varying electrical current in response to the pressure. The proposed self-powered pressure sensor shows a high-performance with a sensitivity of 0.101/kPa, a linearity of R-2 = 0.995, and fast and reversible response to the pressure up to similar to 100 kPa. As practical applications of the proposed sensor, a detection of flexion/extension of a human finger for the manipulation of a prosthetic robot finger and a wind detection for the continuous monitoring of the wind speed and direction have been demonstrated.