Highly flexible, biocompatible, large-scale production of BaTiO3 nanocube (BTO NC)/poly(dimethylsiloxane) (PDMS) composite films (CFs) prepared via a simple, cost-effective solution casting technique are reported for the first time for high-performance piezoelectric nanogenerators (PNGs). The crystalline BTO NCs were synthesized via a simple low-temperature molten salt method. The piezoelectric output performance of the CF was investigated as a function of the weight ratio of the BTO NCs in the polymer matrix, electrical poling, constant mechanical loading, and low-frequency biomechanical energy harvesting. The composite PNG (CPNG) with 15 wt % of BTO NCs displayed an excellent peak-to-peak voltage (Vpp) of 126.3 V and current density (J) of 77.6 μA/cm2 and generated a maximum instantaneous areal power density of 7 mW/cm2 at 100 Mω at the low input mechanical pressure of 988.2 Pa. The generated output was sufficient to drive commercial light-emitting diodes and low-powered consumer electronic devices. Next, the CPNG was tested to harness waste biomechanical energy in our daily life; it generated a Vpp of 29 V (human hand palm force) and 55.9 V (human foot stress). The proposed device was lightweight, flexible, eco-friendly, cost-effective, and a potential candidate to generate high electrical output at low mechanical pressure. © 2017 American Chemical Society.