Cisplatin, a widely used chemotherapeutic agent, is limited by its poor bioavailability, rapid systemic clearance, and severe side effects. To overcome these limitations, hydroxyapatite-gelatin composite microspheres were developed to improve drug entrapment efficiency (DEE) and provide sustained drug release. Various formulations were prepared by incorporating chitosan either by mixing once or through a sequential coating strategy. By adjusting the loading procedure, the DEE increased from 58% to 99%. The composite microsphere effectively controlled the total drug release duration, extending it from one month to over 5 months. Moreover, the MTT assay demonstrated that all samples effectively inhibited cell growth, with cell viability reduced to less than 20% after 2 weeks of experimentation. These findings demonstrate that the sequential chitosan coating method offers superior drug entrapment and prolonged release compared to mixing chitosan once, exhibiting its potential as a sustained drug delivery system for cancer treatment.