LncRNA MIR31HG is involved in many types of cancers, while its roles in breast cancer are still unknown. The current study aimed to explore the function of lncRNA MIR31HG in breast cancer and the underlying mechanisms. Stable expression cell lines were constructed by using lentivirus particles. MTT assay was used to determine cell viability. Wound healing and Transwell assay were used to determine cell migration and invasion, respectively. The changes in biomarkers were determined by using qPR-PCT and Western blotting, respectively. BALB/c nude mice were used to generate a xenograft mouse model. MIR31HG regulated cell proliferation, migration and invasion in MCF7 cells. Besides, MIR31HG regulated N-Cadherin, Vimentin, and E-Cadherin. MIR31HG positively regulated receptor-interacting serine-threonine kinase 4 (RIPK4), as supported by the fact that knockdown of MIR31HG suppressed RIPK4, and the knockdown of RIPK4 did not affect MIR31HG. Additionally, we found that RIPK4 regulated cell proliferation, migration and invasion in MCF7 cells. The changes in RIPK4 regulated N-Cadherin, Vimentin, and E-Cadherin. Consistently, in vivo studies showed that the knockdown of MIR31HG or RIPK4 reduced tumor size in xenograft animal models. The roles of lncRNA MIR31HG in breast cancer were associated with its regulatory effects against RIPK4.