Dental demineralization is a widespread problem and the main responsible for dental caries and dentin hypersensitivity. Dental caries is a biofilm-driven bacterial infection that causes mineral depletion in enamel and is associated with an increased prevalence of medical rehabilitative polymeric implants. Since existing tissue-engineering methods are incapable of manufacturing synthetic dentin adhesive, modern therapeutic interventions address the remineralization of caries-infected dentin to prevent its inevitable removal. In recent years, magnetic nanoparticle-coated adhesives were known to deliver drugs to the pulp and get better adhesive penetration into dentin. In the present study, we prepared and assessed the effectiveness of antimicrobial peptide (cecropin A) coated Fe₃O₄-nanoparticle on dentin remineralization, bond strength, and its antibiofilm potential against Streptococcus mutans, is associated with dental caries in humans. Prior to the experiment, the synthesized cecropin@Fe₃O₄ nanoparticle was characterized and assessed its antibiofilm potential against S. mutans. The transcriptomic approach with qPCR analysis stated that cecropin@Fe₃O₄ nanoparticle significantly downregulated the expression of biofilm-regulated genes such as GtfB, GtfC, GtfD, VicR, ComDE, and Smu0630 in S. mutans, which validates the outcome of in vitro results. Interestingly, the prepared cecropin@Fe₃O₄-nanoparticle coated adhesive effectively increased the dentin remineralization and bond strength. Fascinatingly, cecropin@Fe₃O₄ adhesive significantly hindered the biofilm formation of S. mutans on the dentin surface. Notably, the cecropin@Fe₃O₄ adhesive accomplished reduced biofilm CFU count, lactic acid production, and biofilm metabolic activity. In addition, the cecropin@Fe₃O₄ adhesive also reduced the biofilm formation of other caries-associated bacterial pathogens, including S. sobrinus, S. sanguinis, and S. mitis. Overall, the current research found that the cecropin@Fe₃O₄ adhesive was more effective in remineralizing dentin lesions with antibiofilm potential in order to avoid Streptococcus-derived dental caries.