Background: The glycosylation of constant regions of antibodies significantly affects their interaction capabilities with immune cells. It is a modification that, in addition to the biological activity of antibodies, has an impact on their conformation, stability, solubility, secretion, pharmacokinetics, and immunogenicity. The location of glycosylations on the molecule is essential for the proper function of the antibody, as is the structure of the individual glycans. Changes in the glycosylation profiles of antibodies have been described in some physiological processes like pregnancy or ageing, but also in many pathological conditions such as rheumatoid arthritis or gastric, lung and prostate tumours. There are still several unexplained mechanisms that control the glycosylation of antibodies or immune responses, which in turn are regulated by these modifications. Multiple sources describe the importance of some specific glycosylations as potential biomarkers. Purpose: The aim of this review is to summarise and present the knowledge of the glycosylation of antibodies and to highlight their influence on immune responses and their role during disease. Their importance is also underlined by the fact that the most of these therapeutic antibodies used and developed are modified by glycosylation. The targeted introduction of appropriate glycosylations, which can promote activities such as antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis or complement-dependent cytotoxicity, have improved the ability of these antibodies to kill pathogens or tumour cells. Therefore, more attention is being paid to this area. In the future, more effective tools for diagnosing and treating certain diseases can be created with better knowledge.