Objective To systematically evaluate the efficacy and safety of pyrotinib-based therapy in patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer based on real-world data, and to explore factors associated with prognosis. Methods A total of 102 patients with HER2-positive advanced breast cancer who received pyrotinib at Zhongshan Hospital, Fudan University, were included retrospectively from January 1, 2019, to January 31, 2024, and prospectively from February 1, 2024, to November 30, 2025. Follow-up was conducted until March 31, 2026. Clinical and follow-up data of the patients were collected, and survival analysis was performed by Kaplan-Meier method. Prognostic factors were analyzed through multivariable Cox regression and logistic regression. Results Among the 102 patients, the median follow-up duration was 31.3 months, the median progression-free survival (PFS) was 12.9 months, the median overall survival (OS) has not been reached (estimated to be 64.8 months), and the objective response rate (ORR) was 35.29%. Multivariate Cox regression analysis revealed that lung metastasis (HR＝2.562，P＝0.006), third-line and subsequent treatment (HR＝3.857，P＝0.010), and pyrotinib monotherapy (HR＝3.682，P＝0.015) were associated with shorter PFS. Eastern Cooperative Oncology Group performance status (ECOG PS)≥2 (HR＝16.948，P＜0.001) and third-line and subsequent treatment (HR＝3.958，P＝0.034) were associated with shorter OS. No associated factors related to ORR were found. Regarding safety, diarrhea was the most common adverse event, occurring in 74.51% of patients. Conclusions In real-world clinical practice, pyrotinib-based therapy demonstrated clinical efficacy and manageable safety in patients with HER2-positive advanced breast cancer. Lung metastasis, pyrotinib monotherapy, ECOG PS≥2, and pyrotinib administration in multiple lines of therapy may affect patient prognosis.