Ovarian cancer (OC), a highly lethal gynaecological malignancy, is often diagnosed at advanced stages, resulting in a poor prognosis. Sialylation, an important form of glycosylation, significantly contributes to the progression of various solid tumours, including OC. Aberrant sialylation promotes tumour progression and metastasis by altering the structure and function of glycoproteins. Although its role in several solid tumours is well documented, the role of abnormal sialylation in OC and its potential as a therapeutic target remain poorly understood. This review highlights sialylation as a key regulator of the progression, metastasis, and drug resistance of OC. A deeper understanding of altered sialylation can contribute to the identification of novel therapeutic strategies for OC.