The impact of decorating the Y (Y = Ti or Sc) atom on the procarbazine (PA) drug delivery performance of an AlP nano-sheet (AlP-NS) was investigated by performing DFT calculations. It was found that the pristine AlP-NS was not a good choice for the drug delivery of PA. Decorating Ti and Sc into the AlP-NS surface increased the adsorption energy of PA from −6.2 to −29.7 and −31.9 kcal/mol, respectively. The Y atom considerably contributed to the generation of virtual orbitals of Y-decorated AlP-NS, which showed that these atoms were more suitable for a nucleophilic attack compared to Al. Finally, the adsorption performance and capacity of PA increased after the decoration of the Y atom, which made the nano-sheet more suitable for the drug delivery of PA. In cancerous cells with a low pH, PA was significantly protonated, which led to the separation of PA from the Y-decorated AlP-NS surface.