•High power density energy harvesting with hybrid perovskite composites •Hybrid perovskite piezoelectric sensors are able to monitor delicate human motions •Interfacial molecular interactions between the hybrid perovskite and polymer Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices. Piezoelectric hybrid organic-inorganic perovskites (HOIPs) have emerged as promising materials for the development of self-powered electronic devices. These hybrid systems generally have low elastic moduli and are also intrinsically brittle, limiting their applications in mechanical-to-electrical energy conversion. Here, we report the synthesis of TMCM-CdCl3/PDMS (TMCM, trimethylchloromethyl ammonium; Cl, chloride; PDMS, polydimethylsiloxane) composites with high piezoelectricity. The TMCM-CdCl3 micro-rods can adhere with PDMS chains via the C–H···Cl interactions, leading to effective absorption of strain and corresponding efficient conversion to electric polarization. As a result, the energy harvesting devices made by the composite films give a high power density up to 115.2 μW/cm2, catching up with those of the state-of-the-art ceramic counterparts. In addition, the composite devices can harvest human motion energy and sense delicate body gestures. This work demonstrates that the piezoelectric HOIP/polymer composites can serve as promising materials for the development of self-powered flexible and wearable devices.