Ensuring food safety amid the growing prevalence of naturally occurring contaminants such as mycotoxins and food allergens remains a critical global imperative. These xenobiotic agents, originating from fungal metabolism and allergenic proteins, respectively, pose substantial threats to public health, necessitating the development of rapid, reliable, and field-deployable detection technologies. This chapter delineates the recent paradigm shift toward biosensor-based diagnostics, offering a nuanced synthesis of their operational principles, biomolecular recognition elements, and physicochemical transduction mechanisms. Emphasis is placed on the integration of nanostructured materials, molecular imprinting, and aptameric systems to augment sensor sensitivity, selectivity, and operational stability. Moreover, this chapter explores advanced modalities including electrochemical impedance spectroscopy, surface plasmon resonance (SPR), and gravimetric assays, highlighting their utility in detecting trace-level contaminants across complex food matrices. The translational potential of these systems is further enhanced through their convergence with Internet of Things (IoT) frameworks and artificial intelligence (AI) for predictive analytics and real-time supply chain surveillance. Finally, regulatory harmonization, standardization of reference materials, and integration into HACCP-based critical control strategies are discussed as essential enablers for the widespread commercial adoption of biosensor technologies. Collectively, these advancements underscore the pivotal role of biosensors in fortifying global food safety systems through intelligent, multiplexed, and decentralized analytical platforms.