Electrochemical supercapacitors (ESs) still need to overcome development obstacles in order to realize their full potential while being acknowledged as a crucial part of all energy storage and conversion technologies. As developed, a fine one-dimensional nanomaterial in the form of MnO2 nanowires could be a key finding to extract the true potential of ES. The X-ray diffraction (XRD) and Raman analysis confirm the formation of the pure β-MnO2 phase. The sample possesses a nano rod-like structure with a diameter of about 45–65 nm, which provides a high specific surface area and a high surface-to-volume ratio. The MnO2 nanowires show a specific capacitance of 212.85 F g−1 at a current density of 0.2A g−1 with capacitance retention of > 97.5% and a coulombic efficiency of > 98% even after 5000 cycles. Also, the fabricated symmetric supercapacitor provides a high specific capacitance of 37.57 F g−1 at a current density of 0.2Ag−1. It shows high capacitance retention of about 101.1% with > 109% coulombic efficiency even after 5000 cycles.