Breast cancer (BC) is the most common malignant tumor in women. Although overexpression of CD155 has been detected in many types of human cancer cells, it is not completely understood about its expression and function in BC and its prognostic significance. In the present study, we detected the expression level of CD155 in 216 cases of BC by immunohistochemistry (IHC), and we evaluated its relationship with BC patients’ clinical information. We also analyzed the characteristics of CD163, CD8, and CD68 in 216 cases of BC patients through IHC. The results indicated that the CD155 expression level was significantly associated with primary tumor size (x² = 23.593, P < 0.001), lymph node metastasis (x² = 15.426, P < 0.001), tumour–node–metastasis (TNM) stage (x² = 19.693, P < 0.001), Ki-67 (x² = 9.355, P = 0.002), and CD163/CD8/CD68 expression on statistical analysis. BC patients with high expression of CD155 had poor overall survival rate, on both univariate analysis (Hazard ratio = 2.681, 95% CI = 1.458–4.928, P < 0.001) and multivariate analysis (Hazard ratio = 2.029, 95% CI = 1.059–3.887, P = 0.033). These results suggest an interaction between CD155 expression and tumor-infiltrating lymphocytes (TILs) in BC, and they also suggest that CD155 could be an effective prognostic biomarker for BC.