Programmed Death-Ligand 1 (PD-L1) overexpression as a predictive biomarker for anti-PD-1/PD-L1 therapy effectiveness has been observed in various human malignancies and contributes to poor prognosis. However, this is still controversial in breast malignancy. This cross-sectional analytic study of 37 invasive breast carcinoma patients’ formalin-fixed paraffin-embedded blocks was conducted to assess the association between immunohistochemical expression of PD-L1 and various clinicopathological parameters. PD-L1 was expressed in 48.6% of the invasive breast carcinoma specimens. PD-L1 positive expression was significantly associated with larger tumor size, higher histological grade, high stromal TILs, and aggressive molecular subtype, such as triple negative breast cancer. The association of PD-L1 expression with adverse clinicopathological characteristics indicates that PD-L1 expression can be considered as a prognostic biomarker for invasive breast carcinoma, and may be helpful in selecting potential patients for anti-PD-1/PD-L1 therapy.