Regarding the important role of microRNAs in breast cancer, investigating the molecular mechanisms of miRs and their impacts on breast cancer progression is critical. Thus, the present work aimed to investigate the molecular mechanism of miR-183 in breast cancer. PTEN was validated by dual luciferase assay as a target gene of miR-183. Through qRT-PCR analysis, miR-183 and PTEN mRNA levels in breast cancer cell lines were measured. To determine the impacts of miR-183 on cell viability, the MTT assay was used. Moreover, flowcytometry was applied to analyze the effects of miR-183 on the cell cycle progression. To detect the effects of miR-183 on the migration of BC cell lines, wound healing was used along with a Trans-well migration assay. Western blot was utilized to assess the effect of miR-183 on PTEN protein expression. MiR-183 can exert an oncogenic effect by promoting cell viability, migration, and cell cycle progression. It was revealed that cellular oncogenicity is positively regulated by miR-183 by inhibiting the expression of PTEN. According to the present data, miR-183 may play a vital role in the progression of breast cancer by reducing PTEN expression. It may be also a potential therapeutic target for this disease.