Developing efficient oxygen evolution reaction (OER) catalysts using transition metals (TMs) is critical for enhancing electrocatalytic water splitting. This study examines the OER performance of Fe–Ni–S layered double hydroxide (LDH) nanostructures with sulfate-ion intercalation in various hierarchical configurations. These LDH hierarchical structures are electrodeposited in different processes, including one-step electrodeposition of FeS nanoflakes, NiS nanoflowers, and FeNiS nanoflowers, as well as two-step electrodeposition of FeNiS@NiS nanoflakes and FeNiS@FeS nanoflowers. The variation in heterostructure configurations considerably influences the morphology of the electrodeposited films, promoting the formation of interfacial synergy pathways between various active bonding states. The hierarchical FeNiS@FeS LDH nanoflowers demonstrate the optimal hetero structure combination for enhanced OER performance, exhibiting low overpotentials of 226 and 234 mV to reach current densities of 50 and 100 mA cm 2 , respectively, and a low Tafel slope of 27 mV•dec LDH structures exhibit high stability for 50 h at 50 mA cm 2 1 . All hierarchical . Notably, the fabricated FeNiS@FeS LDH nano f lowers outperform those reported in previous studies.