Simple Summary: The Melanoma Antigen Gene (MAGE) belongs to the larger family of cancer testis antigens. The MAGEA family were the first tumor-associated antigens identified at the molecular level whose expression was consistent in most human cancers and germinal cells. Aberrant expression of MAGEA family is noted in a majority of human malignancies, where they are associated with increased cancer cell proliferation, survival, and resistance to various therapies. This makes them an ideal biomarker and attractive therapeutic target in designing novel therapies. This review mainly focuses on the opportunities for the development of MAGEAs as promising biomarkers and their therapeutic implications in bladder cancer. The Melanoma Antigen Gene (MAGE) is a large family of highly conserved proteins that share a common MAGE homology domain. Interestingly, many MAGE family members exhibit restricted expression in reproductive tissues but are abnormally expressed in various human malignancies, including bladder cancer, which is a common urinary malignancy associated with high morbidity and mortality rates. The recent literature suggests a more prominent role for MAGEA family members in driving bladder tumorigenesis. This review highlights the role of MAGEA proteins, the potential for them to serve as diagnostic or prognostic biomarker(s), and as therapeutic targets for bladder cancer. [ABSTRACT FROM AUTHOR]