In this research, Fe3O4@SiO2@NTMPThio-Cu was introduced as a novel and green heterogeneous nanocatalyst with a dendrimer template that is environmentally friendly and reusable based on Fe3O4@SiO2. In this way, magnetic silica nanoparticles were first modified with cyanuric chloride, followed by melamine and thiosemicarbazide, and ultimately, it’s decorated with the cost-effective metal copper. The synthesized nanocatalyst was characterized by various analyses such as FT-IR, XRD, SEM, TGA, and EDX. The efficiency of Fe3O4@SiO2@NTMPThio-Cu was measured in one-pot synthesis of xanthene and spirooxindole-pyran derivatives under mild solvent-free conditions. High efficiency, excellent yield of products, mild reaction conditions, simple operation, no use of toxic organic solvents, and reusability of this catalyst increase the attractiveness of this technique for large-scale environmentally friendly operations.