<p>Stem-like T cells (T_SL) represent a distinct subset of CD4⁺ and CD8⁺ T cells characterized by self-renewal, multipotent differentiation, and long-term persistence, and have emerged as pivotal regulators of immune responses in chronic disease contexts. Despite growing interest, the developmental programs, molecular signatures, and clinical relevance of T_SL remain incompletely understood, limiting their translational potential. Recent evidence highlights the central role of key transcription factors such as TCF-1 and BCL6, metabolic circuits including the Wnt-β-catenin and STAT3 pathways, and microenvironmental signals in sustaining the identity and function of T_SL subsets. In various pathologies—including chronic infections, cancer, autoimmunity, and transplant rejection—T_SL cells contribute to both immune persistence and pathogenic activation through their capacity to replenish exhausted effectors or differentiate into inflammatory subtypes. These cells not only shape immune trajectory but also hold promise as dynamic biomarkers and therapeutic targets. Targeted modulation of T_SL via cytokine supplementation, immune checkpoint blockade, adoptive transfer, or niche interference is under investigation, with encouraging results in preclinical and early translational studies. This review outlines the molecular regulation and functional diversity of stem-like CD4⁺ and CD8⁺ T cells, evaluates their disease-specific roles, and discusses strategies to harness or inhibit these populations for precision immunotherapy.</p>