miRNAs contain suppressive and oncogenic properties to regulate the progression of cancers. The expression of miR-125b expression is reported to be consistently low in breast cancers. However, the function and mechanism of miR-125b are not fully understood in breast cancers. In our study, our objective is to identify the DEGs and biological processes in the miR-125b mediated breast cancer cells by analyzing the RNA-seq data. The GSE123358 dataset was produced by the Illumina HiSeq 2000 (Homo sapiens). The KEGG and GO analyses showed the mitochondria and endoplasmic reticulum oxidative phosphorylation pathways are the main processes in miR-125b mediated breast cancer. Moreover, we identified ten interactive molecules including UQCRQ, CALR, HNRNPU, ATP5G1, NDUFB11, UQCRH, HSP90B1, TGOLN2, SAP18, and XPOT. Thus, our study may benefit the treatment of breast cancer by using miR-125b.