Herein, a lamellar structured nano-graphene oxide supported ionic liquid/Fe complex (NGO/IL–Fe) is prepared through grafting of alkyl imidazolium chloride on the NGO followed by treatment with iron(III) chloride hexahydrate. The NGO/IL–Fe nanomaterial was characterized by using FT-IR, PXRD, TGA, EDX and SEM techniques. NGO/IL–Fe was used as a robust and efficient nanocatalyst for the synthesis of tetrahydrobenzo[b]pyrans in water at 25 °C. The desired products were obtained in high yield over a relatively short time. The recoverability, reusability and also leaching tests were performed to study the stability and the nature of the designed catalyst under applied conditions.