In this study, the Fe3O4 nanoparticles were encapsulated in the hyperbranched poly L-lysine citramid (HBPLC). The Fe3O4-HBPLC nanocomposite modified with L-arginine and quantum dots (QDs) to obtain Fe3O4-HBPLC-Arg/QDs as a new photoluminescent and magnetic nanocarrier for the pH-responsive release and targeted delivery of Doxorubicin (DOX). The prepared magnetic nanocarrier was fully characterized using different techniques. Its various potential as a magnetic nanocarrier was evaluated. The in-vitro drug release studies exhibited that the prepared nanocomposite has pH-responsive behavior. The antioxidant study revealed good antioxidant properties of the nanocarrier. Also, the nanocomposite revealed excellent photoluminescence with a quantum yield of 48.5 %. Cellular uptake studies showed that Fe3O4-HBPLC-Arg/QD has high cell uptake in MCF-7 cells and can be used for bioimaging applications. In-vitro cytotoxicity, colloidal stability, and enzymatic degradability studies revealed that the prepared nanocarrier is non-toxic (with cell viability of 94%), stabile and biodegradable (about 37%). The nanocarrier was hemocompatible with 8% hemolysis. Also, according to the apoptosis and MTT assays, the Fe3O4-HBPLC-Arg/QD-DOX induced greater toxicity and cellular apoptosis against breast cancer cells about 47.0 %.