A chitosan supported Dy(III) nanocatalyst was synthesised by a simple procedure. It was used as a catalyst for one pot, three component synthesis of hexahydropyrimidine derivatives. All the reactions were completed in a short time period at room temperature and the products were obtained in high to excellent yields. The catalyst was characterized by FT-IR, XRD, SEM-EDX, TEM and ICP-AES analyses. The stability of the catalyst was evaluated by TG analysis. Use of water, ambient conditions, recyclability and high TOF of the catalyst make this protocol a sustainable alternative to existing protocols.