MnCoP/(Co,Mn)(Co,Mn)₂O₄ nanocomposites were prepared by hydrothermal + annealing + phosphating treatment method and their electrochemical properties were investigated, systematically. Aqueous MnCoP/(Co,Mn)(Co,Mn)₂O₄//active carbon asymmetric supercapacitor demonstrate the capacitance of 74.14 F/g at 0.1 A/g and good rate performance and cycling stability(maintained 85.75 % of the initial capacitance after 10,000 GCD cycles at a current density of 0.5A/g). Furthermore, all-solid-state asymmetric supercapacitors assembled by MnCoP/(Co,Mn)(Co,Mn)₂O₄ nanocomposites exhibit the capacitance of 123.43 F/g at a current density of 0.5 A/g, an energy density of 132.3 Wh/kg at a power density of 503.4 W/kg, good rate performance and cycling stability. Especially, the all-solid-state supercapacitors connected in series present excellent voltage extendtion capability and the ones assembled in parallel demonstrate outstanding capacitance retention capability, highlighting the promising practical applications of MnCoP/(Co,Mn)(Co,Mn)₂O₄ nanocomposites to meet various output requirements in electrochemical enenrgy storage.