Background: High expression of leucine-rich alpha-2-glycoprotein 1 (LRG1) is closely related to angiogenesis, which may play an important role in promoting invasion and metastasis. However, the current literature has yet to clarify the clinical significance of LRG1 in breast cancer. Objectives: The purpose of this work was to validate the correlation between LRG1 expression and prognosis in early breast cancer. Methods: We utilized an LRG1 detection agent in 330 cases of early breast cancer. The correlation of LRG1 expression with clinicopathological features, patient recurrence, and survival was investigated. Results: Compared with adjacent tissue samples, an elevated expression of LRG1 was observed in breast cancer samples. Moreover, LRG1 expression is associated with the number of lymphatic metastases and TNM pathological stage (p = 0.000, p = 0.000, respectively). For disease-free survival (DFS), the Kaplan-Meier curve indicated a poorer prognosis for the group with high LRG1 levels compared with the low LRG1 group (p = 0.000). A similar result was found for overall survival (OS; p = 0.000). The multivariate Cox regression indicated that LRG1 was still associated with DFS (HR 2.090, 95% CI 1.205-3.625, p = 0.009) and OS (HR 2.112, 95% CI 1.167-3.822, p = 0.013). The histological grade, TNM pathological stage, and molecular subtype were identified as independent risk factors affecting OS. Conclusion: In the malignant progression of breast cancer, high LRG1 levels are associated with lymphatic metastasis, histological grade, poor DFS, and poor OS. This study validates the use of LRG1 as a potential prognosis biomarker for early breast cancer.