One of the major issues associated with industrial production of menaquinone-7 (MK–7) is the low fermentation yield. In this study, we investigated the effect of iron oxide nanoparticles coated with 3–aminopropyltriethoxysilane (IONs@APTES) on the production of MK–7 using B. subtilis (ATCC 6633). Decoration of B. subtilis cells with IONs@APTES significantly enhanced both MK–7 production and yield. An approximately two-fold increase in MK–7 production (41 mg/L) was observed in the presence of 500 µg/mL IONs@APTES, as compared to MK–7 production using untreated bacteria (22 mg/L). This paper, therefore, illustrates the immense biotechnological potential of IONs@APTES in increasing MK–7 concentration using B. subtilis, and its future role in bioprocess engineering.