Food preservative additives, whether synthetic or naturally derived, work by slowing down the deterioration of food caused by microbial growth, enzyme activity, and oxidation. As a green and natural food preservative, curcumin is low-toxic and biocompatible at the concentrations typically employed for food preservation, with potential in functional foods via multiple mechanisms. However, despite extensive research, critical gaps remain in understanding the precise molecular mechanisms underlying its preservative effects, and its practical application continues to be limited by poor stability and low water solubility. This review provides a critical synthesis of current knowledge on curcumin’s mechanisms and application strategies in food preservation, moving beyond descriptive summaries to evaluate evidence strength, identify methodological limitations, and highlight contradictory findings. Specifically, we critically examine the relationship between curcumin’s molecular structure and biological functions, assess delivery systems’ efficacy in overcoming its addressing limitations, and propose a future research framework integrating mechanistic investigation with application-oriented development.