Abstract: Human epidermal growth factor receptor 2 (HER2) tyrosine kinase inhibitors (TKIs), including lapatinib, pyrotinib, neratinib, and tucatinib, have become major therapeutic options for HER2-positive breast cancer. However, the use of these agents are often associated with adverse events, of which diarrhea is one of the most common and clinically significant. Diarrhea not only negatively affects the physical health of patients but also significantly impairs their quality of life, potentially leading to treatment delays or discontinuations. Therefore, the effective management of diarrhea is crucial to ensure patient adherence to HER2-TKI therapy and improve the patients’ quality of life. Currently, no multidisciplinary expert consensus in China exists regarding the management of anti-HER2-TKI-related diarrhea in breast cancer. Spearheaded by the Breast Cancer Integrative Rehabilitation Professional Committee of China Anti-Cancer Association, domestic experts from multiple disciplines, including breast oncology, pharmacy, gastroenterology, nutrition, and traditional Chinese medicine, jointly developed a multidisciplinary expert consensus on the management of TKI-associated diarrhea in HER2-positive breast cancer. This consensus was formulated through a comprehensive review of domestic and international guidelines, relevant literature, and evidence-based medical research while considering the clinical practice in China. This consensus aims to provide clinicians with a set of multidisciplinary, comprehensive guidelines for managing diarrhea associated with anti-HER2-TKIs to enhance the overall treatment outcomes and quality of life of patients with HER2-positive breast cancer.