Curcumin, a natural polyphenol derived from Curcuma longa, is known to modulate a multitude of cellular signaling pathways. Despite its promising pleiotropic medicinal properties, the clinical application of curcumin has been significantly hindered by its inherent limitations, including poor solubility in plasma, low chemical stability, rapid systemic metabolism, and consequently, low bioavailability. Transforming growth factor-beta (TGF-β) is a multifunctional cytokine that plays a central and often paradoxical role in regulating cell growth, differentiation, and immune responses. Dysregulation of TGF-β signaling is critically involved in various facets of cancer biology, including tumor initiation, progression, invasion, and metastasis. This research was designed to investigate the anticancer potential of a curcumin-containing nanoemulsion on the MCF-7 human breast cancer cell line, with a specific focus on elucidating its effect on the expression of the TGF-β gene. A stable curcumin nanoemulsion was synthesized and characterized. Dynamic Light Scattering (DLS) analysis confirmed a uniform and small particle size with a mean diameter of 12.3 nm. The efficiency of curcumin encapsulation within the nanoemulsion matrix was calculated to be a high 70%. The cytotoxic potential of the formulation was evaluated on MCF-7 cells using the MTT assay, which determined the half-maximal inhibitory concentration (IC50) to be 13.54 µg/mL. Subsequently, MCF-7 cells were treated with this IC50 concentration to assess changes in gene expression. Real-Time Quantitative PCR (RT-qPCR) results revealed that treatment with the curcumin nanoemulsion induced a significant 2.1-fold decrease in the mRNA expression level of the TGF-β gene compared to untreated control cells, with a high statistical significance (p=0.0001). This study concludes that the curcumin nanoemulsion exerts its anticancer effects, at least in part, by downregulating the TGF-β signaling pathway. These findings underscore the potential of this nano-formulation as a novel therapeutic strategy for breast cancer treatment.