MicroRNAs (miRNAs) are often aberrantly expressed in breast cancer and are postulated to play a role in its initiation and progression. In the present study, we found that the expression level of miR-24-3p was upregulated in breast cancer in comparison with the level in adjacent normal tissues. Overexpression of miR-24-3p was able to promote cell proliferation and inhibit cell apoptosis in MDA-MB-435 and MDA-MB-468 cells. With the bioinformatic method, we further identified that p27Kip1 is a direct target of miR-24-3p, and its protein level was negatively regulated by miR-24-3p. Therefore, the data reported here demonstrate that miR-24-3p is an important regulator in breast cancer, and imply that the miR-24-3p/p27Kip1 axis has potential as a therapeutic target for breast cancer.