Single-walled carbon nanotubes (SWCNTs) are regarded as the primary candidate materials for optoelectronic devices in the post-Moore era due to their unique two-dimensional quantum confinement effect, high carrier mobility, and tunable bandgap structure. However, the intrinsic SWCNTs feature strong chemical inertness, easy agglomeration, and fixed band structure, which greatly restrict their performance in complex optoelectronic systems. Therefore, this paper focuses on bandgap renormalization induced by sp³ hybridization, Fermi level shift caused by charge-transfer doping, exciton binding energy modification via dielectric environment screening, and the influence of chiral-selective modification on circular dichroism. Based on the established Hamiltonian perturbation model and many-body Green’s function theory framework, the physical picture of macroscopic reconstruction of the photoelectric response of SWCNTs by functional groups as artificial defects or dielectric coating layers is revealed from a microscopic perspective, providing a theoretical basis for the design of high-performance and multifunctional carbon nanotube optoelectronic devices.