BACKGROUND: Dysbindin domain-containing 1 (DBNDD1) is strongly connected with the occurrence and development of malignancies, but the DBNDD1 function and mechanism in invasive breast cancer (IBC) remain poorly understood. Our objective was to ascertain the possible diagnosis and prognostic importance of DBNDD1 in IBC. METHOD: An analysis was done to ascertain the connection between the DBNDD1 expression level in IBC and clinicopathological features employing the relevant databases, and to evaluate DBNDD1 in the diagnosis and prognosis of IBC. We explored possible cellular mechanisms and biological functions as well as explored DBNDD1-related interacting proteins, analyzed DBNDD1 methylation status, and investigated its correlation with immune cell infiltration. The effect of DBNDD1 on the function of breast cancer (BC) cells was studied in vitro. RESULT: DBNDD1 mRNA and protein levels exhibited higher expression in IBC, and were significantly correlated with a worse outcome. DBNDD1 hypomethylation status was linked to a negative prognosis. Enrichment analysis revealed that the genes exhibiting a positive correlation with DBNDD1 expression were mostly enriched in pathways linked to DNA synthesis and DNA methylation. Furthermore, the DBNDD1 expression level exhibited a substantial correlation with the immune cell infiltration in tissue. DBNDD1 overexpression emerged to enhance the BC cell's proliferation, invasion and migration as well as suppress the BC cell's apoptosis, as validated by in vitro tests. CONCLUSION: DBNDD1 upregulation is directly linked to the tumor immune cell infiltration and the unfavorable IBC prognosis. DBNDD1 possesses the capacity to be a biomarker for diagnosing and predicting the outcome of a disease, as well as a possible target for therapeutic interventions in IBC.