Conductive carbon cloths (CCs) have been great attention as a promising current collector for flexible supercapacitors that supply power to portable and wearable electronics. However, the hydrophobic surface and weak adhesion with active materials has limited to be adopted as the binder-free and flexible electrode with mechanical/electrochemical stability. In this work, we demonstrate preparation of binder-free and flexible electrodes based on polyaniline (PANI) on carbon cloth. Polydopamine (PDA) layer are used to impart hydrophilicity, leading to uniform growth of PANI on the hydrophobic surface of carbon. Furthermore, PDA layer improves adhesion strength between PANI and carbon substrates, which allows for superior mechanical stability under ultrasonic condition. PANI-based flexible electrode shows high areal capacitance (160.8 mF cm− 2 at 0.5 mA cm− 2), good rate capability (71.1% even at high current density of 10 mA cm− 2), and long-term cycling stability (82.6% capacitance retention after 1500 cycles). Furthermore, a quasi-solid-state flexible supercapacitor reveals remarkable mechanical flexibility and durability, with superior capacitance retention (~ 100%) in bent state and after repetitive 1000 cycles.