Breast cancer (BC) is one of the major causes of cancer death among women around the world, and the available therapeutic strategies still need to be improved. Monosaccharides, as a natural product, possess the capability to impair the growth of cancer cells, which has been confirmed, but the efficacy of L-arabinose on the epithelial–mesenchymal transition (EMT) of tumor cells remains unclear. In the present study, we found that L-arabinose treatment significantly influences EMT marker protein (N-cadherin, E-cadherin and Vimentin) expression and decreases migration and invasion potential in vivo and in vitro. Mechanistically, L-arabinose induced autophagy and abrogated the nuclear and cytoplasmic expression of β-catenin in BC cells. After adding the Wnt/β-catenin activator LiCl, the efficacy of s on the EMT of BC cells was reversed. Intriguingly, the expression of β-catenin was elevated by the suppression of autophagy using sh-Atg5 lentivirus under L-arabinose treatment. Here, we found L-arabinose contributed to the inhibition of the epithelial–mesenchymal transition (EMT) in breast cancer cells. Moreover, the suppressive effects of L-arabinose on the EMT were regulated by autophagy in BC cells. In addition, we demonstrated that L-arabinose affected the EMT via down-regulating the Wnt/β-catenin signaling pathway, which is dependent on autophagy. Thus, this study provides a novel potential drug for breast cancer therapy.