Breast-conserving surgery is an important therapeutic approach that aims to preserve breast appearance and quality of life while ensuring oncological safety. Accurate lesion localization and achievement of negative margins are key factors affecting local control and decisions regarding reoperation. At present, localization and margin assessment in breast-conserving surgery are evolving from experience-based judgment to image-guided decision-making, from two-dimensional localization to three-dimensional spatial assessment, from purely morphological recognition to the integration of functional and molecular information, and from manual interpretation to artificial intelligence-assisted decision support. Techniques such as wire-guided and clip-based localization, intraoperative ultrasound, specimen radiography, and intraoperative frozen pathological assessment have been widely used in clinical practice. However, these techniques still have certain limitations in assessing non-palpable lesions, microcalcifications, multifocal disease, and residual lesions after neoadjuvant therapy. In recent years, dye tracing, three-dimensional specimen imaging, radiofrequency spectroscopy, optical imaging, molecularly targeted fluorescence imaging, and artificial intelligence-assisted interpretation have gradually been applied in breast-conserving surgery, providing new approaches to improving the objectivity of lesion identification, margin assessment, and intraoperative decision-making. In patients at increased risk of positive margins, including those with invasive lobular carcinoma, multifocal disease, or unclear residual disease extent after neoadjuvant therapy, comprehensive evaluation should integrate intraoperative multimodal imaging reassessment, specimen imaging, rapid pathological assessment, and, when necessary, emerging imaging techniques. This review summarized commonly used and emerging techniques for precise localization and margin assessment in breast-conserving surgery for breast cancer patients, with the aim of providing a reference for the rational selection and clinical translation of these technologies.