Recently, the construction of morphology and structure is considered to be one of the key factors to improve the cycle stability and rate performance of nanomaterials. Herein, MnCo2S4/NiCo2S4 (MCS/NCS) composites with three-dimensional network structures were fabricated by simple electrodeposition of NiCo2S4 nanosheets on the MnCo2S4 nanosheets framework. Compared with the two-dimensional nanosheet structure, the three-dimensional network structure of MCS/NCS has good capacitive and conductive properties. Also, the effects of electrodeposition time on the morphology and electrochemical properties of the composites were studied. Among them, MCS/NCS-6 stands out for its unique structure and excellent electrochemical properties, exhibiting excellent specific capacity (920 C g−1 at a current density of 1 A g−1) and good cycling stability. More importantly, the fabricated asymmetric supercapacitor MCS/NCS//AC assembly has a high energy density of 45.6 Wh kg−1 (800 W kg−1 power density) and good cycle life (75.6%, 10,000 cycles), demonstrating the potential application of this uniquely structured electrode material in alkaline aqueous energy storage devices such as asymmetric supercapacitors (ASC).