Breast cancer is one of the most prevalent malignancies in women worldwide. Although great progress has been achieved in the diagnosis and treatment of breast cancer, the prognosis of patients with breast cancer is still poor due to distal recurrence and metastasis after surgery. This study demonstrated that the expression level of ankyrin repeat domain 22 (ANKRD22) in human breast cancer tissues was significantly higher than that in normal breast tissues. ANKRD22 knockdown inhibited the proliferation, invasion, and epithelial-mesenchymal transition (EMT) of breast cancer cells. Further research indicated that ANKRD22 regulated the expression of nucleolar and spindle-associated protein 1 (NuSAP1) and then the activation of Wnt/β-catenin signaling pathway. Moreover, overexpression of NuSAP1 reversed the inhibitory effects of ANKRD22 knockdown on the proliferation, invasion, and EMT of breast cancer cells. In summary, this study demonstrated that ANKRD22 enhanced breast cancer cell malignancy by activating the Wnt/β-catenin pathway via modulating NuSAP1 expression, which might shed light on new therapeutic approaches for breast cancer.