Food adulteration significantly threatens public health, consumer trust, and economic stability, necessitating advanced detection methods to ensure food safety and authenticity. Optical sensor arrays have emerged as a promising solution due to their simplicity, cost-effectiveness, and potential for on-site analysis. This chapter provides a comprehensive overview of optical sensor arrays, focusing on their principles, architectures, and applications in detecting food adulteration. Unlike traditional selective sensors, optical sensor arrays employ semi-selective or cross-reactive elements to generate unique response patterns, or “fingerprints,” enabling the identification and quantification of adulterants in complex food matrices. This chapter explores the fundamental principles of optical sensor arrays, including their ability to detect changes in optical properties, such as color, fluorescence, and absorbance. It also discusses the classification of sensor elements, including substrates, and the role of digital imaging and multivariate statistical analysis in signal processing. Applications of optical sensor arrays are detailed across various food products, including coffee, soft drinks, milk, water, sugars, meat, honey, oils, and saffron, demonstrating their versatility and effectiveness in combating food adulteration. By integrating optical sensing with advanced computational techniques, these arrays offer rapid, reliable, and accessible solutions for food safety and quality assurance, paving the way for a future where food authenticity is more easily verifiable.