Oxidative stress (OS), resulting from an imbalance between reactive oxygen species (ROS) and the antioxidant defense system, plays a critical role in the initiation and progression of cancer. Recent research has highlighted the regulatory influence of non-coding RNAs (ncRNAs) on cancer initiation and development through the regulation of redox homeostasis and key signaling pathways, which makes them potential targets for anticancer therapy. The ncRNA–oxidative stress axis contributes to malignancy through DNA damage, altered signaling, and dysregulated molecular networks. Plant-derived dietary components and phytochemicals have garnered significant attention for their ability to restore ROS balance and modulate the ncRNA/OS axis, thereby inhibiting carcinogenesis and enhancing the efficacy of chemotherapy. To study the interplay between OS, ncRNAs, and the anticancer potential of plant-derived compounds, in this review, we conducted an extensive search of electronic databases to identify and analyze studies that explore the interwork between OS, ncRNAs, and the chemotherapeutic role of phytochemicals. We discuss the dual role of phytochemicals in both cancer induction and suppression, emphasizing their capacity to generate ROS and regulate ncRNA expression. Furthermore, the review underscores the importance of nutritional interventions and antioxidant regulation in cancer chemoprevention and therapy, including the interconnected roles of oxidative stress, ncRNAs, and phytochemicals in cancer development and treatment, with a focus on dietary modulation as a strategic approach in oncology.