Construction of porous form of 3D flower-like nanoarchitectures with controlled morphologies has drawn a considerable interest by scientists in energy storage research field owing to their distinct structural features. Herein, we synthesize 3D flower-like NiMn2O4 nanoarchitectures by an eco-friendly silicon-oil bath strategy via ethylene glycol as an intermediate solvent and subsequent post-calcination in air atmosphere. The obtained various morphologies-based electrode materials result in the dominant battery-like electrochemical behavior. Interestingly, the 3D flower-like NiMn2O4 nanoarchitectures shows a large surface area of 122.8 m2 g−1 which can endow more electroactive sites in electrochemical analysis and exhibit a high specific capacity ~223 mA h g−1 at 2 A g−1 with good cycling stability. This is mainly due to the synergistic behavior of unique 3D flower-like morphology and the porous nanosheets on its surface. Furthermore, a pouch-like hybrid supercapacitor is designed and it delivers a high energy density of 46.4 Wh Kg−1 and power density of 5720 W kg−1. And, it is also demonstrating for its practical usage. Consequently, the proposing synthesis strategy in this report can be a promising facile wet-chemical approach to synthesize the controlled hollow or core-shell structures for energy storage device applications.