The functionalization of liposomes with antibodies is a potential strategy to increase the specificity of liposomes and reduce side-effects of chemotherapeutic agents. The active targeting of Human Epidermal growth factor Receptor 2 (HER2) positive breast cancer cells can be achieved by coating liposomes with an anti-HER2 monoclonal antibody. In this study, we synthesized Calcein and Doxorubicin loaded immunoliposomes functionalized with the monoclonal antibody Trastuzumab. Both liposomes were characterized for size, phospholipid concentration and antibody conjugation. The effect of low-frequency ultrasound (LFUS)-induced drug release was tested using three power densities, 7.46, 9.85 and 17.31 mW/cm2; and the release data were modeled using six different kinetic models. LFUS results established the sonosensitivity of both carrier types, with immunoliposomes being more acoustically sensitive than control liposomes. Results also showed an increase in the release rate as the power density increased from 7.46 to 17.31 mW/cm2. Finally, the in vitro cell experiments showed enhanced uptake and cytotoxicity when breast cancer cell lines, SKBr3 and MDAMB-231, were treated with LFUS-triggered HER-liposomes.