Abstract In the recent past, drug delivery through nanoparticles is considered an effective tool to treat various diseases. Biopolymeric nanoparticles such as protein based nanoparticles have vital role as drug carrier as it is non-antigenic, and easily biodegradable. Curcumin, plant polyphenolic anticancerous compound was loaded into the casein nanoparticles by coacervation method. Particle size and surface charge of spherical casein nanoparticles as observed to be 201.4 nm and -86.9 mV. The loading efficiency of curcumin loaded casein nanoparticles was found to 85.05 %. In vitro drug release was performed at different pH (7.4 and 3.0), and the cumulative release was observed to be 24.8 and 20.13% and at different temperatures (25°C and 37°C), the cumulative release was observed to be 24.8 and 28.60 % respectively in 48 h. Curcumin release from casein nanoparticles was shown to be in a steady, and prolonged rate. The nanoparticles were observed to have an effective antimocrobial activity than curcumin in free form. The drug loaded casein nanoparticles were found to be potent particles to protect cells from hydrogen peroxide and UV light damage. The cytotoxic activity of nanoparticles on MCF7 and A549 cells were assayed and was observed to have an IC50 value of 609 and 825.2µg/ml. Cell death was observed to be through apoptosis, accompanied by DNA fragmentation.