• Fullerene (C60) induces a reverse transformation of bulk mesophase pitch into spherical mesophase microbeads, contrasting with conventional liquid-phase carbonization.
• At 300–320 °C with 5% C60 loading, coalesced naphthalene-based mesophase pitch converts to spherical microbeads, with size increasing at higher temperatures.
• The induction effect is attributed to C60's nanoscale nucleation and π-electron interactions with aromatic molecules, enabling controllable morphology transformation.
• This work provides a new method for tailoring mesophase pitch morphology, with potential applications in carbon materials science and engineering.