BACKGROUND: The B-aggressive lymphoma (BAL) proteins, including BAL1, BAL2, and BAL3, constitute a conserved protein family characterized by their N-terminal macro domains and putative C-terminal poly (ADP-ribose) polymerase (PARP) active site. Dysregulation of BALs has been closely associated with the progression of various cancers. However, there is limited understanding of their precise expression profile, prognostic significance, and role in breast cancer (BC). METHODS: The expression patterns of BALs were evaluated utilizing multiple databases, including Ualcan, Gene Set Cancer Analysis (GSCA), Search Tool for the Retrieval of Interacting Genes/Proteins (STRING), and Gene Expression Profiling Interactive Analysis (GEPIA). The prognostic significance of BALs was assessed via Kaplan-Meier plotter analysis. Furthermore, the potential mechanisms underlying the contribution of BC progression were predicted through GO and KEGG pathway enrichment analysis. Additionally, the effect of BALs on the malignant behaviors of BC cells was determined using CCK-8 assay, Transwell assay, and TUNEL assay. RESULTS: The data revealed that the expression levels of both BAL1 and BAL2 were upregulated in BC, whereas no significant change was observed for BAL3. Survival analysis demonstrated a strong association between the overexpression of both BAL1 and BAL2 and favorable prognosis in patients with various subtypes of BC, including estrogen receptor (ER)-positive, ER-negative, Basal, luminal B, HER2-, and HER2 + subtypes. Additionally, the knockdown of BAL1 and BAL2 inhibited the proliferation and migration of BC cells while facilitating apoptosis. CONCLUSIONS: These findings suggest that both BAL1 and BAL2 hold great potential as significant prognostic biomarkers and therapeutic targets for patients with BC.