<p>Rational design and doping of complex metal oxides offer a powerful strategy to overcome the performance limitations of supercapacitor (SCs). This work presents triethanolamine (TEA) assisted pure MnV₂O₄ and molybdenum (Mo) doped MnV_0.95Mo_0.05O₂ ternary metal oxide (Mo-TMOs) for symmetric SCs device with tailored nanostructures synthesized by hydrothermal method to optimize electrochemical performance. Comprehensive structural and morphological analyses confirm uniform Mo distribution and the formation of highly interconnected nanostructures that promote rapid ion diffusion and electron transport. Incorporation of Mo into the ternary oxide framework successfully tunes electronic conductivity, increases redox activity and enhances structural stability. Detailed morphological, structural, and compositional investigations confirm that Mo was successfully integrated and the created a defect-rich homogeneous architecture. Electrochemical analysis of the prepared supercapacitor device shows that the pure and Mo doped TMOs exhibits exceptional cycling stability of 94.7% and 96.3% at 5 Ag^− 1 after 5000 cycles and high specific capacitance of 317.92 Fg^− 1 for pure and 349.70 Fg^− 1 for Mo doped sample at 10 mVs^− 1. Both synthesized samples possess high BET surface area of 53.55 and 68.90 m²/g. The fabricated device delivers high energy and power density values of 28.25 WhKg^− 1 at 917.35 WKg^− 1 and 31.08 WhKg^− 1 at 924.82 WKg^− 1 for pure and Mo doped samples respectively. These findings highlight the potential of Mo-doped ternary metal oxides as promising electrode materials for next-generation high-performance SCs devices.</p>