<p>Advancing the development of efficient, low-cost electrocatalysts for the oxygen reduction reaction was of paramount importance for the advancement of clean and sustainable energy equipment, including supercapacitors. This study aimed to synthesize CoS nanosheets and FeOOH nanorods through a simplified one-step process to facilitate the growth of heterogeneous composite structures on carbon cloth. The FeOOH@CoS core–shell nanostructure flexible electrode was successfully synthesized, resulting in a material that exhibited excellent electrochemical performance in both supercapacitors and catalytic oxygen generation. The optimal amount of FeOOH electrodeposited on in situ-grown CoS nanosheets on carbon fiber cloth was investigated to develop a novel FeOOH@CoS electrocatalyst. The coupling between FeOOH and CoS generated a remarkable synergistic effect, which significantly enhanced the catalytic properties of FeOOH@CoS for the oxygen evolution reaction. As a result, the FeOOH@CoS composite demonstrated exceptional catalytic performance, exhibiting both high electrocatalytic activity and long-lasting cycle stability. Notably, the catalytic performance of FeOOH@CoS surpassed that of pristine FeOOH and outperformed standard commercial electrocatalysts by a significant margin. In the structured OER evaluation, the overpotential was measured at 287&#xa0;mV at a current density of 10&#xa0;mA&#xa0;cm⁻². Furthermore, the FeOOH@CoS nanocomposite exhibited remarkable cycling stability, retaining 87.6% of its initial current density after 40&#xa0;h of chronoamperometric testing. For performance testing of supercapacitors, the discharge time reached 3233&#xa0;s, with a Cs value of 419 F g⁻¹. The stable catalytic performance of the FeOOH@CoS electrocatalyst was attributed to three main factors: a regulated electronic structure that accelerated charge transfer, the formation of abundant oxygen vacancies that promoted catalytic activity, and the heterostructure formed by FeOOH and CoS.</p> Graphical Abstract <p></p>