The flexible electrodes with battery-like capacitive active materials or efficient electrocatalysts are highly desirable for flexible electronics and portable devices. Here we develop a highly flexible Ni₃S₂@Ni/CC electrode via a facile and scalable nickel electroplating and in-situ sulfuration route. When it acts as a supercapacitor electrode, the assembled all-solid-state hybrid supercapacitor delivers a high areal energy density of 0.27 mWh cm^-2 at an areal power density of 4.90 mW cm^-2. Because of its superior mechanical flexibility, the assembled supercapacitor exhibits 88.1% retention of its initial capacitance after 2000 bending cycles from 0° to 90°. Furthermore, the Ni₃S₂@Ni/CC electrode exhibits high activity for oxygen evolution reaction (OER), achieving a benchmark of 10 mA cm^-2 at a relatively low overpotential (η₁₀) of 290.9 mV with a Tafel slope of 101.26 mV dec^-1. Slight increments of 9.9 mV in η₁₀ and 6.55 mV dec^-1 in Tafel slope are obtained even when the electrode is tested under a bending angle of 180°. Meanwhile what it delivers an excellent long-term durability for 30 h that is similar to the electrode without bending for OER. The flexible Ni₃S₂@Ni/CC electrode can be incorporated into wearable electronics and portable water-splitting cells.