BiFeO3 (BFO) is a popular multiferroic material exhibiting robust antiferromagnetic and ferroelectric properties and is a promising candidate for use in sensors and transducers. In this work, BFO piezoceramics were synthesized by a simple hydrothermal method and were incorporated into the copolymers PVDF-TrFE and PVDF-HFP to fabricate flexible nanocomposite films. BFO nanoparticles (NPs) act as nucleating agent inside the polymer matrix, thus improving the overall performance of the piezoelectric film. The phase purity of the synthesized BFO NPs was confirmed by XRD and the β-phase content of the fabricated film was calculated from FTIR analysis. The nanocomposite film PVDF-TrFE/BFO with 6 wt% filler loading (PTB6) showed better piezoelectric performance among others. The intrinsic functional properties of the composite film were evaluated by P-E (polarization-electric field) hysteresis loop test. Further, the nanocomposite film, after corona poling, was used for fabrication of a flexible piezoelectric nanogenerator (PNG). The poled films exhibited better piezoelectric as well as dielectric properties. The fabricated PTB6 based PNG generated a maximum of 18.5 V under a biomechanical finger tapping force. This study suggests that the proposed flexible device is a potential candidate for driving low-power electronic devices.