Flexible pressure sensors have played an increasingly important role in the Internet of Things (IoT) and human–machine interaction (HMI) systems. However, it is in a desire to fabricate the sensor with high sensitivity and low power consumption. In this paper, we have developed a self-powered triboelectric pressure sensor based on chemically modified micropatterned PDMS. Different wire meshes serve as template to fabricate microstructures on the triboelectric layer. To enhance the triboelectric output performance, introducing functional groups to the surface of the triboelectric layer to expand triboelectric polarity difference. By virtue of the cooperative effect of enhanced contact area variations from the PDMS microstructure’s gradual deformation, the reduced dielectric thickness as well as the increased charge density from the extended triboelectric polarity difference originated from chemical modification, the self-powered triboelectric sensor displays a sensitivity of 44.31 V kPa⁻¹ in the range of 0.006–2 kPa and 7.16 V kPa⁻¹ in the range of 2–8.5 kPa. Additionally, the self-powered triboelectric sensor is efficient in human motions measurement. This work provides a route to fabricate high-performance pressure sensor with morphological and chemical modification on the triboelectric polymers.