This study investigates the development of a novel and environmentally friendly catalyst, FeO@chitosan@NiB nanocomposite, for multicomponent reactions (MCRs). Chitosan (CS), a biopolymer, is used because it is biocompatible, abundant, and has functional groups that can be complexed with metals. Nickel boride (NiB) is used in hydrogenation reactions due to its catalytic properties. The magnetic properties of FeO nanoparticles enable easy separation. Herein, we describe the successful synthesis of the FeO@CS@NiB nanocomposite and its use in MCRs for the green synthesis of tetrahydrobenzo[]pyran derivatives. These heterocyclic compounds impress with their diverse biological activities. The research has several advantages, including the implementation of environmentally friendly catalyst protocols, the simplification and cost-effectiveness of the synthesis process, the use of an easily accessible biopolymer, the successful performance of efficient one-pot reactions without additional waste generation, and the easy recycling of the catalyst. This research demonstrates the potential of FeO@CS@NiB as a promising catalyst for sustainable and selective MCRs.