Chronic diseases like cardiovascular disease (CVD), diabetes, cancer, and neurodegenerative conditions are still chief global health challenges, driven by aging populations and modifiable lifestyle factors. This chapter tries to discover the growing role of functional foods (FFs) in chronic disease prevention, emphasizing their bioactive components besides mechanisms of action. FFs—whether naturally occurring or intentionally modified—contain compounds like omega-3 fatty acids, antioxidants, peptides, glucosinolates, and probiotics, which exhibit physiological benefits beyond basic nutrition. These bioactive components lessen inflammation, control metabolism, and boost cellular resilience, contributing to enhanced public health. Also, the chapter describes the FFs’ classification, their strategy of formulation, and their targeted effects on specific chronic diseases. By integrating interdisciplinary insights from nutrition science, biochemistry, and public health, this work highlights the potential of FFs as a preventive and therapeutic tool in modern food interventions.