There are multiple forms of treatment for cancer treatment, but since the treatment process also damages healthy cells. Accordingly, in recent years, in the light of nanotechnological studies, cancer cell targeted drugs known as smart drugs have attracted attention. Niosome is one of the preferred nanoparticle systems in these studies. Bromelain is a protease mixture obtained from the pineapple stem or fruit. In recent years, it has been shown in many cell types that it has anticancer properties due to its proteolytic activity. In this study, bromelain was encapsulated into niosomes with 32±2.9% efficiency for the treatment of breast cancer, which is the most common type of cancer in women. Specific targeting of niosome-encapsulated bromelain to HER2+ SKBR-3 cell line was performed by trastuzumab (herceptin) conjugation. DLS, FTIR, XPS, TEM were used for particle characterization. Niosomes (Nio) showed particle size of 134.3±8.1nm, Bromelain loaded niosomes (Nio-Br) showed particle size of 165.6±11.5nm. As a result of TEM analysis, it was shown that morphologically spherical and targeted sizes of niosomes of approximately 100nm were synthesized. FTIR and XPS analyzes were performed to confirm pegylation and trastuzumab conjugation. Cytotoxicity and apoptosis studies of Nio-Br, Nio-Br-PEG-Tra, Tra samples carried out in SKBR-3 and MDA-MB-231 cell lines. Determined IC50 values of final product on SKBR-3 and MDA-MB-231 cell lines respectively 77.51±5.39 μg/mL and 238.1±16.62 μg/mL. As a result of in vitro studies, final product is more toxic on HER2+ SKBR-3 cell line thanks to trastuzumab in structure. At the same time final product has more apoptotic effect connected to toxic characteristic. Formed molecule in this study was designed for HER2+ breast cancer cells. According to obtained in vitro experiment results, this designed molecule has potential to be drug delivery system for HER2+ breast cancer.