Introduction: Suicide in adolescents poses a major public health crisis as the second leading cause of death in youth. Suicidal thoughts and behaviors (STBs) are a principal reason for psychiatric hospitalization among adolescents. Numerous studies across development have identified risk factors (e.g., depression, borderline personality (BPD) features, family history of suicide) associated with STBs, while research in adults largely reports that the affective component of psychopathy, captured by callous-unemotional (CU) traits, is negatively associated with STBs. However, the relationship between CU traits and STB risk among adolescents remains unclear. Methods: The present study tested associations between self-reported CU traits and STBs in a high-risk sample of adolescents (N = 396, Mage = 14.5, SDage = 1.6) hospitalized for psychiatric inpatient acute care, 84% of whom were admitted for STBs. A series of hierarchical regressions were utilized to test the association between CU traits and STB outcomes, including clinician-rated STB severity, any endorsement of lifetime suicidal ideation (SI) or suicide attempt (SA), total number of self-reported SAs, and any report of a past medically serious SA according to clinician judgement, and to test whether CU traits moderated the influence of STB risk factors on these outcomes. Results: Hierarchical linear regression analyses revealed that, overall, CU traits were related to lower STB severity (B = -0.034, SE = 0.017, p = 0.046), even after controlling for known risk factors. Upon further inspecting which dimensions of STB severity were related to CU traits, a negative association between CU traits and any lifetime SI was found (B = -0.034, SE = 0.020, OR = 0.096, p = 0.006). However, significant interactions were found between CU traits and family history of suicide for clinician-rated severity of suicidal behavior (B = 0.044, SE = 0.022, p = 0.044) and any lifetime SA (B = 0.052, SE = 0.026, OR = 1.053, p = 0.047), such that negative associations between CU traits and SB outcomes were diminished in the presence of this STB risk factor (i.e., positive family history). Further, though no main effect of CU traits was observed for SA lethality, a significant interaction between CU traits and a latent variable of aggregated STB risk, capturing symptoms of depression, BPD, affective lability, impulsivity, and trauma, (B = 0.018, SE = 0.008, OR = 1.018, p = 0.035) indicated an "exacerbating" effect of CU traits on the association between these risk factors and SA lethality. No main or interaction effects were found for total number of lifetime SAs. Conclusion: CU traits may protect against STBs in the absence of major risk factors but "increase" STB risk, particularly the severity of suicidal behaviors including the medical seriousness of SA, among adolescents already at elevated risk. These novel findings support the need for clinicians to consider CU traits when conducting suicide risk assessments, particularly with adolescents in acute care or high-risk settings. Finally, these findings support prior work that suggests adolescents with elevated CU traits, including those with co-occurring psychopathology, warrant effective interventions tailored to their unique needs, which may include careful safety planning. [Note: The publication year (2023) shown on the PDF is incorrect. The correct publication year is 2025.]