Clinical staging models are tools used in healthcare that have the potential to enhance diagnostic precision, improve treatment decisions, articulate more personalized care pathways, and optimize service models. In youth mental health, clinical staging has been increasingly applied to conditions where progression from non-specific symptoms to full-blown syndromes, such as schizophrenia, bipolar disorder, and depression, is possible. However, novel transdiagnostic staging models have also been proposed, recognizing the limitations of current classification systems and the substantial overlap of symptoms, particularly early in the illness course. Models incorporating an appropriate developmental and transdiagnostic lens may offer significant advances for research and clinical practice, supporting early intervention and secondary prevention. This narrative review critically examines theoretical premises and empirical applications of transdiagnostic clinical staging models in youth. Peer-reviewed studies were identified in PubMed using search terms related to clinical staging, focusing on sociodemographic, cognitive, and clinical factors investigated in youth samples (12-30 years). Evidence is synthesized in three main sections: progression, extension, and stage-based treatment. Additionally, a stage-based care model and directions for future research are presented. Early findings partially support important assumptions for the model, suggesting stage-related differences in cognition and functionality. Furthermore, new extension features have been recently proposed, including substance use, circadian disturbances, and physical illnesses. The long-term outcomes of stage-based interventions remain an open question. While the transdiagnostic clinical staging model offers a promising alternative for classifying youth psychopathology, further empirical validation is essential before its widespread implementation.