CXCR4 possesses a critical role in several intracellular events such as chemotaxis, invasion and adhesion, which are associated with metastasis of cancer cell. In this study, CXCR4 targeted polymeric nanoparticle was developed for delivering cytotoxic drug and blocking the chemokine induced migration of cells expressing CXCR4. A peptide which was a linear form of CXCR4 antagonist (LFC131) was attached to PLGA nanoparticles (LFC131-NPs) and PLGA nanoparticles encapsulating DOX (LFC131-DOX-NPs). The cellular binding and internalization of LFC131-DOX-NPs were investigated. The binding and internalization of LFC131-DOX-NPs were higher and more rapidly compared to unconjugated NPs. LFC131-NPs blocked SDF-1α induced migration of BT-549-Luc cells. MTT assays demonstrated that LFC131-NPs and LFC131-DOX-NPs decreased cell viability in a dose dependent manner in 24, 72 and 120 h incubation. A treatment concept of blocking breast cancer cell migration from interaction with SDF- 1α by using LFC131-NPs and then attacking breast cancer cells with doxorubicin might increase the efficacy of current breast cancer treatment.