Magnetic-responsive biopolymer composites have great potential for use in diverse biomedical applications. In this study, a new nanobiocomposite consisting of carbon nitride (CN), carboxymethyl cellulose (CMC) hydrogel, silk fibroin biopolymer, and magnetic iron oxide nanoparticles (Fe₃O₄ MNPs) was designed and fabricated. The synthesis procedure is based on the modification of the CN platform with CMC hydrogel and conjugation with SF biopolymer alongside in-situ magnetization with Fe₃O₄ MNPs. This hybrid magnetic nanobiocomposite was characterized by several analytical methods: FT-IR, EDX, SEM, XRD, TGA, and VSM. The in-vitro hemolysis assay confirmed the hemocompatibility of the prepared nanobiocomposite and its anticancer activity against breast cancer cell lines (BT549) was evaluated by MTT assay. Furthermore, the magnetic nanobiocomposite showed excellent potential for hyperthermia applications, with a maximum specific absorption rate of 7 W/g for 1 mg/mL of the sample under a magnetic field in different frequencies (100, 200, 300, and 400 MHz) and 5 to 20 min time intervals.