Background <p>This study addresses the complex associations between current suicidal symptoms, lifetime suicide attempt history, C-reactive protein (CRP) levels, and executive dysfunction among young people with major affective disorders.</p> Methods <p>A total of 171 young people with major affective disorders presenting varying levels of suicidal symptoms and 97 healthy young people aged 12 to 24 years were recruited for this study. Current suicidal symptom severity was classified as none, mild, or strong if an individual has scores of 0, 2–3, and ≥ 4, respectively, on item 10 of the Montgomery–Åsberg Depression Rating Scale (MADRS). The presence of a lifetime history of suicide attempts was also determined. All participants had CRP levels measured and underwent the Wisconsin Card Sorting Test (WCST).</p> Results <p>Generalized linear models (GLM) with adjustments for demographic characteristics, diagnoses, and non-suicidal depressive symptoms indicated that patients presenting strong suicidal symptoms had the highest CRP levels (<i>p</i> = 0.004) and percentage of nonperseverative errors on the WCST (<i>p</i> = 0.002), whereas those with mild suicidal symptoms were more likely to have intermediate CRP levels relative to non-suicidal young people. Only young people with a history of suicide attempts exhibited an increased percentage of perseverative errors on the WCST (<i>p</i> = 0.023) compared with the healthy controls.</p> Discussion <p>Our findings suggest that CRP levels and the percentage of nonperseverative errors on the WCST served as concurrent markers of suicidality, whereas the percentage of perseverative errors served as a trait marker of suicidality among young people with major affective disorders.</p>