Food freshness is critical to ensuring food safety, minimizing food waste, and improving industrial efficiency. Traditional sensory evaluation and laboratory-based detection methods suffer from inherent limitations, including strong subjectivity, time-consuming procedures, and destructive sampling, which make it difficult to meet the requirements of modern supply chains for rapid, non-destructive, and real-time monitoring. This review comprehensively summarizes the mainstream research directions and recent advances in food freshness monitoring technologies across three complementary directions: (1) biomimetic or instrumental systems based on digital identification of food odors, tastes, and appearance characteristics, including electronic noses, electronic tongues, and machine vision technology; (2) biosensor-based technologies for ultrasensitive recognition of specific biomolecules (metabolites, proteins, and nucleic acids); (3) spectroscopic and imaging techniques for “fingerprint” capture and quantitative analysis of internal components. In addition, the preparation principles, instrumentation, and applications are stated in each section, along with critical performance aspects such as stability and anti-interference capability in complex matrices. We hope this review can provide a comprehensive understanding of sustainable and real-time food quality control for the advancement of food freshness assessment.