 Cobalt sulfide is one of the attractive materials for the energy storage electrodes due to its high specific capacitance (CF) and cost-effective properties. Well-defined nanostructures with promising features are intensively designed to achieve highly effective energy storage electrodes. In this study, a three-dimensional (3D) cobalt sulfide hydrangea macrophylla is successfully synthesized using a simple one-pot method by adding 1-dodecanethiol with long carbon chains as the sulfur and carbon layer sources. The morphology and the corresponding electrochemical performance of cobalt sulfide are examined in views of the vulcanization temperature and duration, as well as the annealing temperature and the loading mass. A CF value of 324.17 F g− 1 is obtained for the cobalt sulfide hydrangea macrophylla-based energy storage electrode at a scan rate of 10 mV s− 1 with the optimized loading mass on flexible nickel foam, owing to the large surface area and improved conductivity benefitted from the hydrangea macrophylla nanostructure and the carbon layer surrounded the cobalt sulfide, respectively. The utilization of this promising hydrangea macrophylla nanostructure of cobalt sulfide on energy storage electrodes opens a window for establishing structure-controlling techniques to improve the electrochemical performances.