Protein kinases represent key nodes for the integration of multiple intracellular signalling pathways, resulting in modulation of both ligand-dependent and ligand-independent mechanisms of sex steroid receptor (sSR) signalling cascades. The proline-directed Ser/Thr kinases including mitogen-activated protein kinases and cyclin dependent kinases were especially reported to contribute to the function and activity of sSRs. The relevant effects of these kinases are well-documented but the impact of glycogen synthase kinase-3 (GSK-3), another member of this kinase family, has been underestimated. Indeed, the specific role of GSK-3 regarding the different sSRs will help to understand further the complexity of sSR signalling. So far, AR and ERalpha were identified as GSK-3 substrates. Additionally, the docking properties of GSK-3 were demonstrated to play a crucial role in sSR signal transduction. Reciprocally, GSK-3 was described as a potential target of non-genomic effects of sSRs. Therefore, GSK-3 regulates and is regulated by sSRs. This review focuses on the emerging and promising involvements of GSK-3 regarding the signalling cascade of the respective sSRs. This review represents a necessary complement of information to highlight the importance of GSK-3 regarding sSR function and activity.