A rapid surge in the research on self-powered bio-electronics is occurring toward the challenge that the state-of-the-art bio-devices require obsolete bulky batteries, which limit device miniaturization and lifespan. Among them, flexible piezoelectric materials that enable mechanical-to-electrical energy conversion, stimulate tremendous attraction to harvest mechanical energy from the motions of human and organs. Here, we report a cost-effective one-step process based on unique two-dimensional mica substrates to fabricate flexible piezoelectric energy harvesters, extending beyond prior art for all-inorganic flexible piezoelectric materials. As an exemplary demonstration, an all-inorganic, large scale, flexible piezoelectric Pb(Zr0.52Ti0.48)O3 energy harvester is fabricated with an outstanding performance (i.e., open-circuit voltage of 120V, short-circuit current density of 150μAcm−2 and power density of 42.7mWcm−3), which are comparable to those via conventional “grow-transfer” technique from rigid substrates to organic soft ribbons, and are much greater by one to four orders of magnitude than previous reported ones based on piezoelectric nanofibers and organic thick films. In particular. This unique process provides a new perspective to fabricate all-inorganic piezoelectric energy harvesters for battery-free bio-electronics.