Here, we demonstrate a nanoengineering strategy that leads to an impact-resistant electrode for flexible energy storage devices such as supercapacitors resulting in state-of-the-art electrochemical performance. A template-less direct vapor synthesis produces a mat of poly(3,4-ethylenedioxythiophene) (PEDOT) 1D nanostructures. A nucleation-controlled self-weaving mechanism is supported enabling rapid synthesis of an electrochemically active flexible electrode in a single step from the vapor phase. Nanofibres self-assemble and “weave” in situ into a micrometer thick porous fibrillar mat characterized by a horizontally-directed interwoven nanofibrillar orientation. A nanofibrillar PEDOT mat is characterized by high conductivity (334 S cm⁻¹), capacitance (164 F g⁻¹) and flexibility (stable upon bending) as well as impact-resistance properties enabling it to withstand an impact energy density of 125 kJ m⁻² and to continue storing energy. After a single 125 kJ m⁻² mechanical impact, a symmetric electrochemical capacitor composed of nanofibrillar PEDOT mats is cycled for 11 000 times with 80% capacitance retention. After forty 125 kJ m⁻² impacts, capacitance degrades by 6% and 1D electrode architecture remains.