MXene has been considered as a promising two-dimensional material for supercapacitors owing to its large surface area, high conductivity, and excellent cycling stability. However, its low specific capacitance restricts its extensive applications. Therefore, to address the issue, we homogeneously deposited NiCo₂S₄ nanoflakes on the surface of MXene on conductive nickel foam (denoted as MXene-NiCo₂S₄@NF), which was used as a composite binder-free electrode for supercapacitor applications. The NiCo₂S₄ nanoflakes increased the surface area of the composite electrode, thereby increasing its specific capacity from 106.34 C g⁻¹ to 596.69 C g⁻¹ at 1 A g⁻¹. Compared to the pristine MXene, MXene-NiCo₂S₄@NF maintained the high retention rate of pristine MXene and exhibited excellent cycling stability with 80.4% of its initial specific capacity after 3000 cycles. The composite electrode exhibited improved electrochemical performance for supercapacitors, owing to the combined merits of NiCo₂S₄ (high specific capacity) and MXene (high retention rate and good cycling stability. The fabricated asymmetric solid-state supercapacitor using MXene-NiCo₂S₄ as a positive electrode and active carbon as a negative electrode, exhibited an energy density of 27.24 Wh kg⁻¹ at 0.48 kW kg⁻¹ of power density.