Breast cancer is the most frequent cause of cancer‑related mortality among women worldwide. The present study aimed to explore the role of magnesium transporter protein 1 (MAGT1) in breast cancer and to illustrate the potential underlying molecular mechanisms. Bioinformatic analysis was performed to explore the association between MAGT1 expression and patients with breast cancer. MTT, colony formation, wound healing and Transwell assays were performed to examine the proliferative, migratory and invasive abilities of MCF‑7 cells. Western blot analysis was conducted to determine the corresponding protein expression. Chromatin immunoprecipitation and luciferase reporter assays were carried out to reveal the interaction between MAGT1 and the Kruppel‑like factor 16 (KLF16). In addition, an experimental animal model was established by the subcutaneous injection of MCF‑7 cells into BALB/c nude mice, and tumor weight and size were measured. The results revealed that MAGT1 expression was upregulated in breast cancer. MAGT1 knockdown significantly suppressed the MCF‑7 cell proliferative, migratory and invasive abilities, and downregulated the protein expression of Ki67, proliferating cell nuclear antigen, MMP2 and MMP9. MAGT1 knockdown also markedly suppressed tumor growth in vivo. Moreover, KLF6 could bind to the MAGT1 promoter and positively regulate MAGT1 expression. The inhibitory effects of KLF6 knockdown on cell proliferation, migration and invasion in vitro, and tumor growth in vivo were partly abolished by MAGT1 overexpression. On the whole, the findings of the present study suggest that MAGT1 knockdown exerts notable inhibitory effects on the progression of breast cancer, providing a potential therapeutic target for the treatment of breast cancer.