Curcumin (CUR) is the active curcuminoid with many physiological, biochemical, and pharmacological properties. Solubility and stability of CUR is the limiting factors for realizing its therapeutic potential. Bovine b-casein is an abundant milk protein that is highly amphiphilic and self-assembles into stable micellar nanoparticles in aqueous solution. b-Casein nanoparticle can solubilize CUR molecules. In the present study, we introduced a drug-delivery system comprising hydrophobic anticancer drug, CUR, entrapped within b-casein-based nanoparticles. The interaction of CUR with b-casein was investigated using steady-state fluorescence spectroscopy and molecular docking calculation. Results showed that at pH 7, CUR molecules bind to b-casein micelle and formed complexes through hydrophobic interactions. Forster energy transfer measurements and molecular docking studies suggested that CUR molecules bind to the hydrophobic core of b- casein. The binding parameters including number of substantive binding sites and the binding constant were evaluated by fluorescence quenching method. Additionally, the cytotoxicity of free CUR and CUR-b-casein complex to human breast cancer cell line MCF7 was evaluated in vitro. The study revealed that the CUR-b-casein complex exhibited better cytotoxic effects on MCF7 cells compared to equal dose of free CUR.