The asteroid 4 Vesta, as the parent body of howardite, eucrite and diogenite (HED) clan of meteorites, preserves a layered core–mantle–crust structure similar to that of Earth, providing critical insights into planetary differentiation in the early solar system. During the core-mantle differentiation of Vesta, whether siderophile elements could reach equilibrium partitioning between the core and mantle depends on their diffusivities in silicate melts, which remain experimentally unconstrained in vestan melts. As siderophile elements, Ga, Mo and W serve as important tracers for the formation and differentiation of Vesta. In this study, diffusion of Ga, Mo and W was investigated at 1300–1600°C and 0.5–1 GPa in a piston-cylinder apparatus for a synthesized vestan basaltic melt with a composition matching polymict eucrite Macibini. LA-ICP-MS measurements revealed error function-shaped diffusion profiles for all three elements, indicating concentration-independent diffusivity. The effect of pressure on diffusivities is negligible. The diffusivities of Ga, Mo and W are comparable, following the diffusivity sequence D(Ga) > D(Mo) > D(W). The activation energies for diffusion of Ga, Mo and W are nearly identical (189 ± 13 kJ/mol). Compared to terrestrial melts, the diffusion of Ga, Mo and W is 1–3 orders of magnitude faster in vestan melt, which can be attributed to its highly depolymerized nature. Based on the available data, we propose empirical diffusivity models for Ga, Mo and W applicable to vestan and terrestrial melts. In light of higher mobility of Fe in basaltic melts, the partitioning of Ga, Mo and W between vestan core and mantle is expected to be hard to reach thermodynamic equilibrium.