Cancer is among the most lethal diseases globally, with incidence rates increasing across diverse subtypes. The escalating burden highlights the demand for innovative cancer therapy strategies for positive outcomes. Among these advancements, bispecific antibodies (bsAbs) have emerged as a promising therapeutic strategy. Bispecific antibodies (bsAbs) are molecules intended to target two different epitopes or antigens. Manipulated bsAb molecules target to create new functionalities, connecting immune cells with tumor cells, and allows multiple formats to optimize the molecular function in specific targeted clinical approaches. Although only two bsAbs have received regulatory approval for clinical application, numerous candidates are currently under investigation in various phases of clinical trials. Their structural customization enables them to perform unique functions, such as bridging immune cells with tumor cells or concurrently inhibiting multiple signaling pathways, thereby enhancing their therapeutic efficacy. The development of bsAbs is driven by novel structural designs and strategic target combinations; however, the high degree of similarity in target selection poses challenges to diversifying bsAb applications. This chapter delves into critical aspects of bispecific antibodies, including their structural design, mechanisms of action, and their ability to mediate immune cell attachment to tumor cells. Additionally, it examines diverse bsAb combinations, target selection strategies, clinical applications, and challenges in their development. This chapter asserts the principles in bsAb engineering, describes current understanding of mechanisms of action, explores future prospects for bsAbs, draws evidence for clinical application, and provides perspectives on challenges and future developments in this field.