Metal hydroxides are versatile and appealing electrode materials owing to their merits such as easy room-temperature synthesis, nanostructures formation, higher conductivity, crystallite or non-crystallite formation, porous structures, etc. Herein, nanostructured ternary transition metal (M= Mo, Co, Fe) hydroxides (TTMHs) are successfully grown on nickel foams via template-free single-step electrodeposition for overall water splitting and supercapacitor applications. Interestingly, numerous element ratios of Mo 5+, Co 2+, and Fe 3+ in the electrodeposition precursor solutions manifested novel nanostructures viz nanosheets, nanoflakes, nanoparticles, and nanograss-like structures were evolved for different precursor solutions. For water splitting, a negative electrode prepared using aqueous Mo: Co: Fe (4.0: 4.0: 2.0 M ratio) metal salt solution that exhibited excellent hydrogen evolution activity with 98 mV overpotential, whereas a positive electrode (Mo: Co: Fe= 3.0: 3.5: 3.5) shows efficient oxygen evolution with 227 mV overpotential, and a full cell assembled from these active electrodes exhibited lower 1.56 V cell voltage at 10 mAcm− 2. For the supercapacitor, a working electrode with composition Mo: Co: Fe= 6.0: 2.0: 2.0 showed 3354.7 mFcm− 2 high areal capacitance at 1.0 mAcm− 2 with excellent retention (91% after 3000 cycles). An asymmetric supercapacitor (ASC) device was fabricated that exhibited enormous energy and power densities of 1.27× 10− 3 Whcm− 3 and 3.75 Wcm− 3, respectively. The high-performances of both devices (water splitting full cell and supercapacitor) are due to the unique composition of hybrid electrodes (with nanostructured morphology) and synergistic effects. The present investigation demonstrates a simple strategy for preparing potential TTMHs composite electrodes with the evolution of different morphologies for multiple electrochemical applications.