Nutrition plays an important role in overall human health. Although there is no direct evidence supporting the direct involvement of nutrition in curing disease, for some diseases, good nutrition contributes to disease prevention and our overall well-being, including energy level, optimum internal function, and strength of the immune system. Lately, other major, but more silent players are reported to participate in the body’s response to ingested nutrients, as they are involved in different physiological and pathological processes. Furthermore, the genetic profile of an individual is highly critical in regulating these processes and their interactions. In particular, miR-155, a non-coding microRNA, is reported to be highly correlated with such nutritional processes. In fact, miR-155 is involved in the orchestration of various biological processes such as cellular signaling, immune regulation, metabolism, nutritional responses, inflammation, and carcinogenesis. Thus, this review aims to highlight those critical aspects of the influence of dietary components on gene expression, primarily on miR-155 and its role in modulating cancer-associated processes.