To address the poor aqueous solubility of the antiepileptic drug carbamazepine, this work systematically investigated the terahertz spectral signatures of carbamazepine (CBZ) and its cocrystals using terahertz time-domain spectroscopy (THz-TDS). The THz absorption spectra of CBZ, saccharin (SA), their physical mixture, as well as cocrystals prepared via dry and wet grinding methods, were experimentally characterized in the 0.5–3.5?THz range. Based on the hydrogen?bond donor/acceptor patterns of CBZ and SA, possible cocrystal configurations were constructed and subsequently optimized by density functional theory (DFT) for spectral simulation. The vibrational origins of the observed THz peaks were elucidated through the automatic recognition and determination (VMARD) approach. Furthermore, the nature and distribution of weak intermolecular interactions were analyzed via force?field?based energy decomposition (EDA?FF) and the independent gradient model based on Hirshfeld partition (IGMH). The results reveal that dry?ground cocrystals exhibit a new absorption peak at 1.98?THz while retaining the characteristic peaks of the individual components, whereas wet?ground cocrystals display six distinct new THz absorption features. Among the predicted polymorphs, crystal form?III provides the best agreement with the experimental spectrum, indicating a three?dimensional packing stabilized by dual and single hydrogen bonds. Vibrational analysis shows that the THz modes of pure CBZ are predominantly attributed to dihedral torsion and bond stretching, while those of the CBZ?SA cocrystal mainly arise from dihedral torsion and bond?angle bending. Although both systems are dominated by van der Waals interactions, supplemented by minor hydrogen?bonding and steric contributions, the spatial distributions differ significantly: in pure CBZ, van der Waals forces are primarily located between stacked aromatic rings, whereas in the cocrystal they are concentrated in regions adjacent to intermolecular hydrogen bonds.