Background: Heat shock A1B, also known as HSP70kDa protein 1B, encodes a 70kDa heat shock protein which is a member of the heat shock protein 70 family. HspA1B is a critical gene which related to many type of diseases by involving in the ubiquitin-proteasome pathway. However, the correlations of HspA1B to prognosis and tumor-infiltrating lymphocytes in different cancers remain unclear. Methods: HspA1B expression was evaluated on the Oncomine database and Tumor Immune Estimation Resource (TIMER) site. We analyzed the influence of HspA1B on clinical prognosis using Kaplan-Meier plotter, the PrognoScan database and Gene Expression Profiling Interactive Analysis (GEPIA). The correlations between HspA1B and cancer immune infiltrates was investigated via TIMER. In addition, correlations between HspA1B expression and gene marker sets of immune infiltrates were analyzed by TIMER and GEPIA. Results: Three cohorts (GSE9195, GSE9893, GSE3494-GPL96)) of breast cancer patients showed that high HspA1B expression was associated with poorer overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS). In addition, high HspA1B expression was significantly correlated with poor OS and progression-free survival (PFS) in bladder cancer, brain cancer and skin cancer. Moreover, HspA1B significantly impacts the prognosis of diverse cancers via The Cancer Genome Atlas (TCGA). HspA1B expression was positively correlated with infiltrating levels of CD4+ T and CD8+ T cells, macrophages, neutrophils, and dendritic cells (DCs) indifferent subtypes of Breast cancer. HspA1B expression showed strong correlations with diverse immune marker sets in BRCA-Luminal. Conclusions: Our findings suggest that HspA1B is correlated with prognosis and immune infiltrating levels of, including those of CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and DCs in multiple cancers, especially in colon and gastric cancer patients. In addition, HspA1B expression potentially contributes to regulation of tumor-associated macrophages (TAMs), DCs, T cell exhaustion and Tregs in colon and gastric cancer. These findings suggest that HspA1B can be used as a prognostic biomarker for determining prognosis and immune infiltration in BRCA-Luminal subtype.