This work describes the development of a modified nanocomposite thermosensitive hydrogel for controlled cisplatin release and improved cytotoxicity with decreased side effects. The system was characterized in terms of physical properties, morphological architecture and in vitro cisplatin release. Cytotoxicity was tested against human colorectal carcinoma HCT-116. In vivo studies were conducted to evaluate the acute toxicity in terms of rats' survival rate and body weight loss. Nephro and hepatotoxicities were evaluated followed by histopathological alterations of various tissue organs. Nanocomposite thermosensitive hydrogel containing nanosized carrier conferred density and stiffness allowing a zero order drug release for 14 days. Enhanced cytotoxicity with 2-fold decrease in cisplatin IC50 was accomplished. A linear in vivo-in vitro correlation was proved for the system degradation. Higher animal survival rate and lower tissue toxicities proved the decreased toxicity of cisplatin nanocomposite compared to its solution.