Two-dimensional (2D) transition metal dichalcogenides (TMDs) attain increasing attention due to their exceptional nonlinear optical efficiencies, which hold promising potential for on-chip photonics and advanced optoelectronic applications. Planar TMDs have been proven to support orders-higher third-order nonlinear coefficients in comparison with common nonlinear materials. Interestingly, stronger light–matter interaction could be motivated when curved features are introduced to 2D TMDs. Here, a type of inorganic fullerene-like ${\mathrm{WS}}_2$ nanoparticles is chemically synthesized using hard mesoporous silica. By using the spatial self-phase modulation (SSPM) method, the nonlinear refractive index $n_2$ and third-order susceptibility ${\chi }^{(3)}$ are investigated in the visible range. It is found that $n_2～{10}^{-5}{\mathrm{cm}}^2/\mathrm{W}$ and ${\chi }^{(3)}～{10}^{-7}\mathrm{esu}$, two orders higher than the counterparts of planar ${\mathrm{WS}}_2$ structures. Our experimental findings provide a fresh thinking in designing nonlinear optical materials and endow TMDs with new potentials in photonic integration applications.