Extensive research has contributed to the current understanding of the critical roles played by long non-coding RNAs in various types of cancer. The present study aimed to investigate the function and mechanism of the long non-coding RNA, MIR4435-2HG (also termed LINC00978), in breast cancer growth and metastasis. Using Gene Expression Profiling Interactive Analysis, an online web tool, it was revealed that MIR4435-2HG was upregulated in breast cancer tissue, and its high expression was associated with poor prognosis based on The Cancer Genome Atlas database. MIR4435-2HG knockdown increased cell apoptosis but decreased cell proliferation, migration and invasion. MIR4435-2HG knockdown increased pro-apoptotic protein expression but decreased anti-apoptotic protein expression. In addition, MIR4435-2HG knockdown leads to dysregulation of epithelial-to-mesenchymal transition-associated genes. Furthermore, knockdown of MIR4435-2HG results in inactivation of the Wnt/β-catenin signaling pathway. The results of the present study demonstrate the tumor-promoting role of MIR4435-2HG in breast cancer progression.