γ-MnS/reduced graphene oxide (γ-MnS/rGO) composite was successfully fabricated via a facile one-pot solvothermal route using graphene oxide (GO), thioacetamide (TAA, CH3CSNH2) and MnCl2·4H2O as reactants. It reveals that TAA plays an important role in reducing GO and sulfurizing γ-MnS. The synthesized composite was characterized via X-ray diffraction and scanning electron microscopy for structural and morphological studies. Electrochemical performance was also investigated through cyclic voltammetry and galvanostatic charge–discharge. As for the application of supercapacitors, the γ-MnS/rGO composite shows a great value of 802.5 F g−1 at a current density of 5 A g−1. Furthermore, the capacitance of γ-MnS/rGO has no decrease of its initial values after 2000 cycles. The galvanostatic charge–discharge curve demonstrates the ideal capacitive behavior of γ-MnS/rGO composite electrodes.