Menaquinone-7 (MK-7) has been identified as an essential nutrient in enhancing bone mineral density, bone health, and reducing the risk of osteoporosis. Although there have been worthy achievements in MK-7 fermentation process using Bacillus subtilis natto, the low yield of fermentation, costly downstream extraction and purification processes remain the main challenges. In this research, a new approach was taken to study the feasibility of the production of a functional fermented dairy-based product rich in MK-7 by the use of iron oxide hydroxide (FeOOH) nanoparticles (NPs) to increase the concentration of MK-7. In this regard, milk a rich source of calcium, a necessary nutrient for bone health was chosen as the fermentation medium for MK-7 biosynthesis using B. subtilis natto. Two different types of FeOOH NPs, namely naked and biocompatible xanthan gum (XG)coated NPs, were synthesised (with 10 nm average particle size) and used to evaluate their effect on developing a fermented dairy-based product rich in MK-7 and iron. According to the results, in the presence of 3 mg/L of XGcoated and 12 mg/L of naked FeOOH NPs, the concentration of MK-7 significantly enhanced, and approximately 27% and 35% more MK-7 biosynthesis were observed respectively as compared with control samples with only 1.9 mg/L MK-7 production.