MicroRNAs (miRNAs) are a class of short non-coding RNAs that play a crucial role in regulating gene expression across multiple levels. They are involved in a wide range of physiological processes, including proliferation, differentiation, apoptosis, and cell cycle control. In recent years, miRNAs have emerged as pivotal regulatory molecules in the development and progression of tumors. Among these, miR-155 has garnered significant attention due to its high expression in various diseases, particularly urologic malignancies. Since an extensive corpus of studies having focused on the roles of miR-155 in various urologic malignancies, it is essential to summarize the current evidence on this topic through a comprehensive review. Altered miR-155 expression is related to various physiological and pathological processes, including immune response, inflammation, tumor development and treatment resistance. Notably, alterations in miR-155 expression have been observed in urologic malignancies as well. The up-regulation of miR-155 expression is commonly observed in urologic malignancies, contributing to their progression by targeting specific proteins and signaling pathways. This article provides a comprehensive review of the significant role played by miR-155 in the development of urologic malignancies. Furthermore, the potential of miR-155 as a biomarker and therapeutic target in urologic malignancies is also discussed.