We report the electrical, dielectric and piezoelectric properties of flexible PDMS-based nanocomposite generators, which are tunable by different contents of multi-walled carbon nanotube (MWCNT, 0.0 -5.0 wt%) and BaTiO3 nanofiber (10-50 wt%). The BaTiO3 nanofiber with tetragonal structure was manufactured by an electrospinning and following calcination process. For the first series of nano composite generators with 30 wt% BaTiO3 nanofiber and 0.0-5.0 wt% MWCNT, both electrical and dielectric properties were dramatically enhanced at a critical MWCNT content of 0.47 wt% owing to the formation of percolating networks of MWCNT in the presence of BaTiO3 nanofibers, as verified by SEM analysis. Accordingly, the nanocomposite generator with 30 wt% BaTiO3 and 5.0 wt% MWCNT achieved the highest conductivity of 0.12 S/cm and dielectric constant of 4474 at 1 kHz, whereas the nano composite generator with 30 wt% BaTiO3 and 2.0 wt% MWCNT attained the best piezoelectric performance by harvesting average output voltage of similar to 3.00 V, current of similar to 0.82 A, and power of similar to 0.14 W. In cases of the second series of nanocomposite generators with 2.0 wt% MWCNT and 10-50 wt% BaTiO3 nanofiber, the electrical conductivity and dielectric constant increased with the increment of BaTiO3 content up to 40 wt%. Overall, the nanocomposite generator with 2.0 wt% MWCNT and 40 wt% BaTiO3 nanofiber generated the highest average output voltage of similar to 3.73 V, current of similar to 1.37 A, and power of similar to 0.33 W, which was feasible to light up commercial LEDs and to charge a capacitor after rectification, revealing the potentiality in powering self-sufficient nanodevices and wireless electronics. (C) 2017 Elsevier Ltd. All rights reserved.