Polyaniline (PANI) as supercapacitor electrode component has received increasing attention due to its high theoretical capacitance, ease of preparation and offers flexibility to fabricate device at low cost. However, PANI suffers from large volume change during doping-dedoping process, and the structural instability becomes more severe at high current and on repetitive cycling, which create challenges in replicating the theoretical capacitance in practical device form. Herein, we demonstrate the fabrication of a PANI based stable and high performance supercapacitor electrode by engineering PANI nano-architecture with NiFe2O4 (NF) nanoparticles. Notably, the optimized composite electrode showed outstanding stability over the pristine PANI electrode for a wide range of charge-discharge current density (1–10 mA/cm2). An all solid state flexible symmetric supercapacitor was fabricated using the optimized composite electrode, which showed high specific and areal capacitance of 334 F/g and 668 mF/cm2 , respectively at 1 mA/cm2 current density. The device also showed excellent cyclic stability with only 1.07 ∗ 10− 3% capacitance loss per cycle for tested >7000 cycles. Noteworthy, the fabricated device showed even higher capacitance when folded and under pressure applied, indicating its suitability to be used in flexible and bendable devices.