Fullerene-based nanomaterials have attracted considerable attention owing to their unique electronic and optical characteristics and their potential applications in photonic and optoelectronic technologies. In the present study, the influence of chlorine functionalization on the electronic structure and optical behavior of C60 fullerene was investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Geometry optimization was performed at the B3LYP/6-31G(d) level, followed by frontier molecular orbital, global reactivity, density of states (DOS), and electronic circular dichroism (ECD) analyses. The calculated HOMO and LUMO energies of chlorinated C60 were −8.28 and −3.55 eV, respectively, yielding an energy gap of 4.73 eV. The derived global reactivity descriptors revealed enhanced electron-accepting ability and favorable charge-transfer characteristics after chlorination. Frontier molecular orbital analysis showed a redistribution of electron density between the occupied and unoccupied states, indicating improved electronic responsiveness. DOS analysis confirmed the semiconducting nature of the modified fullerene and demonstrated the formation of additional electronic states near the frontier orbital region. Furthermore, ECD calculations revealed a significant red shift in the first electronic excitation from 552.01 nm for pristine C60 to 1128.47 nm for chlorinated C60, accompanied by an extension of the optical response into the near-infrared region. The obtained results demonstrate that chlorine functionalization effectively modifies the electronic and optical properties of C60 fullerene, leading to enhanced optical activity and broader spectral responsiveness. These findings suggest that chlorinated fullerene derivatives may serve as promising candidates for future photonic, optoelectronic, and laser-related applications.