Nanomedicines are based on multifunctional particles that may encapsulate active therapeutics within their nanoscale framework, and are capable of releasing the therapeutic payload in an exceedingly specific manner. Metal nanoparticles exhibit remarkable physical and chemical properties which basically depends on particle size and surface configuration. Mainly, gold (Ag) and silver (Au) nanoparticles have been broadly investigated because of their applications in a variety of pharmaceutical fields. At present, a variety of cytotoxic agents have been used in the treatment of breast cancer, but the effectiveness and demerits are unclear. Quercetin is an antioxidant, anticarcinogenic, antimicrobial, antimutagenic, anti-inflammatory and antiallergic. Quercetin has also been shown to reduce human breast cancer cell invasion via down-regulation of MMP-1, -2, and -9 expression. The present study was designed to synthesize silver nanoparticles (AgNPs) using Quercetin and to evaluate potential toxicity and the general mechanism of synthesized AgNPs in MDA-MB-231 human breast cancer cells. The method used for synthesis of nanoparticles was a chemical reduction method. Quercetin is employed as a reducing agent for Silver Nitrate (AgNO₃). AgNPs containing different concentrations of Quercetin were synthesized. Synthesized NPs were evaluated by spectroscopic methods like UV- visible and FTIR spectroscopy, physico-chemical properties and anticancer activities. Thermal analysis of NPs showed a decrease in melting point with endothermic peak at around 130?C. Particle size analysis of NPs showed mean particle size 95.81 nm & 0.091 Polydispesity Index (PDI). The morphological characterization of silver nanoparticles was done using Scanning Electron Microscopy. Zeta potential analysis showed the nanoparticles were stable with values +29.66 mV. The in vitro anticancer activity showed the IC₅₀ value <10 µg and 100% inhibition at 20 µg, whereas pure Quercetin showed IC₅₀ at 13 µg/ml on MDA- MB 231 cell line (human breast carcinoma). Therefore, our findings recommend that the synthesized Quercetin AgNPs could be more cytotxic than pure Quercetin.