Background Long non-coding RNAs (lncRNAs) are novel regulatory molecules in breast cancer development. LncRNA LUCAT1 is a potential tumor promoter in human cancers. In this study, we aimed to explore the role of LUCAT1 in human breast cancer tissues and cells. Methods A total of 31 breast cancer patients who underwent tumor resection, but without chemo- or radiotherapy or acute lung/heart/kidney diseases, provided tumor and adjacent normal tissues. Bioinformatic analysis, qRT-PCR, and luciferase reporter assay were carried out during the study. Results qRT-PCR analysis indicated that, compared with the adjacent tissues and MCF-10A normal breast epithelial cells, LUCAT1 was markedly up-regulated in the breast cancer tissues and five BC cell lines, including MDA-MB-231, MDA-MB-468, MDA-MB-435, SKBR3, and MCF-7. The knockdown of LUCAT1, through the transfection of small interfering RNA (siRNA) specific to LUCAT1, resulted in inhibition of proliferation in breast cancer cells. The expression levels of miR-181a-5p were decreased in the breast cancer tissues and five BC cell lines. Bioinformatic analysis and luciferase reporter assay suggested the interaction between miR-181a-5p and LUCAT1. In addition, the effects of LUCAT1 on promoting cell proliferation were attenuated by overexpression of miR-181a-5p through the transfection of miR-181a-5p mimic. Moreover, bioinformatics and luciferase reporter assay confirmed that miR-181a-5p targeted the 3 '-UTR region of KLF6 and KLF15 mRNA, which were two tumor suppressor genes. LUCAT1/miR-181a-5p axis regulated the expression of KLF6 and KLF15 both in vitro and in vivo. Conclusions Our data indicate that LUCAT1/miR-181a-5p axis can serve as a novel therapeutic target in breast cancer.