Background <p>Suicidal ideation in major depressive disorder (MDD) is typically conceptualized as a function of depressive severity. However, emerging evidence suggests that embodied psychological processes and biological stress pathways may contribute independently. This study examined the associations of interoceptive sensibility and peripheral inflammatory markers with suicidal ideation in MDD, while systematically addressing confounding using entropy balancing.</p> Methods <p>Eighty-three patients diagnosed with MDD were assessed using standardized psychiatric interviews and self-report measures. Interoceptive sensibility was evaluated with the Multidimensional Assessment of Interoceptive Awareness (MAIA-2), childhood trauma with the Childhood Trauma Questionnaire, and depression severity with the Beck Depression Inventory. Peripheral inflammatory indices were derived from fasting blood samples. To examine robustness under increasing confounding control, entropy balancing was implemented under three pre-specified specifications: (Model 1) age and sex; (Model 2, primary) age, sex, and depressive severity; and (Model 3, sensitivity) age, sex, depressive severity, body mass index, and smoking status. Weighted logistic regression models were then fitted for each specification.</p> Results <p>Patients with suicidal ideation exhibited significantly lower Emotional Awareness, and Trusting scores, as well as higher Platelet- Lymphocyte Ratio (PLR) levels. Across all models, higher PLR was consistently associated with increased odds of suicidal ideation. Emotional Awareness was significantly associated with suicidal ideation in Models 1 and 2 but attenuated to non-significance in the most stringently balanced sensitivity model.</p> Conclusion <p>Peripheral inflammation represents a robust biological correlate of suicidal ideation beyond depressive burden, whereas interoceptive emotional awareness appears to be partially embedded within broader depressive process.</p> Trial registration <p>Not Applicable.</p>