A facile coprecipitation approach is used to synthesize CdMn2O4 and a multi-walled carbon nanotube/CdMn2O4 composite. The prepared CdMn2O4 nanoparticles and multi-walled carbon nanotube/CdMn2O4 composite are characterized by numerous characterization techniques and discussed. The TEM characterization reveals that CdMn2O4 nanoparticles are attached with the multi-walled carbon nanotubes (MWCNTs). Further, the supercapacitive performance of CdMn2O4 and MWCNT/CdMn2O4 is investigated. High specific capacities (Qs) of 124.25 and 202 mAh g-1 are obtained at 1 A g-1 from CdMn2O4 nanoparticles and MWCNT/CdMn2O4 composite, correspondingly. The performance of cyclability of MWCNT/CdMn2O4 indicates the long durability of the material for commercial application. Further, an aqueous hybrid supercapacitor (HSC) is assembled by MWCNT/CdMn2O4 and activated carbon (AC). MWCNT/CdMn2O4//AC delivers an energy density of 36.80 W h kg-1 at the power density of 775 W kg-1 with the current density of 1 A g-1. Further, two yellow, two blue, two green, two red and two white color light emitted diodes (LEDs) are easily and separately lighted by two MWCNT/CdMn2O4//AC connected in series. As well, a kitchen timer and toy motor fan were powered by two MWCNT/CdMn2O4//AC connected in series.