Abstract: In the present research, the drug-delivery efficiency of graphitic carbon nitride (g-CN) for melphalan (an anti-cancer drug) was evaluated. To investigate the efficacy of g-CN as a drug-delivery system, the electronic properties of melphalan drug, g-CN, and g-CN-melphalan were calculated at the ground and excited states. The adsorption energy calculated for g-CN-melphalan complex in the water phase is − 1.51 eV. The interactions between g-CN and melphalan were investigated by a non-covalent interactions (NCl) analysis, which showed that there were weak interactions between g-CN and melphalan drug. These low intermolecular forces will allow for easy off-loading of the melphalan at the targeted site. Frontier molecular-orbitals (FMOs) analysis showed that the charge was transferred from melphalan to g-CN during the excitation process. Charge transfer was studied by charge decomposition analysis. Calculations at the excited state revealed that the g-CN-melphalan complex’s λmax showed a redshift of 15 nm and 39 nm in the gas and water phase, respectively. The photoinduced electron transfer (PET) process was studied for 1–2 excited state by using electron hole theory. PET process suggests that fluorescence quenching may take place. The findings demonstrated that g-CN can be used as a drug-delivery system for melphalan drug to treat cancer. This investigation may also encourage more consideration of different 2D substances for drug delivery.