Breast cancer (BC) is a prevalent malignant neoplasm. Utilizing the GEPIA database for analysis and subsequent validation via reverse transcription quantitative polymerase chain reaction (RT-qPCR), we identified that aldehyde dehydrogenase 1 family member A2 (ALDH1A2) exhibits reduced expression and heightened methylation in BC, which is associated with an unfavorable prognosis. In vitro cellular assays demonstrated that the over-expression of ALDH1A2 attenuates the proliferative, invasive, and migratory capacities of breast cancer cell lines, concurrently reducing apoptotic rates. Subsequent investigations employing Methylation-Specific PCR and Western blot analysis in breast cancer cells uncovered that DNA methyltransferase 3B (DNMT3B) is implicated in the DNA methylation of ALDH1A2, with the suppression of DNMT3B leading to an elevation in ALDH1A2 protein levels, thereby establishing an inverse relationship between DNMT3B and ALDH1A2. Furthermore, through the prediction of transcription factors binding to the promoter region of DNMT3B, we discerned that zinc fingers and BTB domain containing 12 (ZBTB12) transcriptionally activates DNMT3B, thereby repressing ALDH1A2 expression. Cellular assays revealed that the knockdown of ZBTB12 or the overexpression of DNMT3B correspondingly inhibits or enhances the proliferative, invasive, and migratory capabilities of breast cancer cells, with DNMT3B abrogating the suppressive effects of si-ZBTB12. Our findings elucidate a novel mechanism involving ALDH1A2 in the progression of breast cancer, where ZBTB12 transcriptionally activates DNMT3B, and the ZBTB12-DNMT3B axis orchestrates the methylation and consequent silencing of ALDH1A2.