Eating disorder symptoms and suicidal ideation are relatively common, and often begin to emerge in adolescence. Interoceptive deficits, or the inability to perceive and accurately identify the physiological condition of the body, is an established risk factor for both eating disorders and suicidal thoughts and behaviors. Despite this, longitudinal research examining the temporal dynamics between these variables is scarce, especially within adolescent samples. Using a three-wave longitudinal design, the present study tested bidirectional relationships between interoceptive deficits, eating disorder symptoms, and suicidal ideation to examine whether interoceptive deficits predicted eating disorder symptoms and suicidal ideation over the course of a year among a sample of adolescents. Participants were 436 community adolescents recruited from local middle- and high-schools. Data were collected at baseline, 6-month follow-up, and 12-month follow-up. Study measures assessed current suicidal ideation, eating disorder symptom severity, and interoceptive deficits. Autoregressive cross-lagged modeling was conducted in MPlus. We found baseline eating disorder symptoms significantly predicted suicidal ideation at 6-month follow-up when controlling for baseline suicidal ideation. Baseline interoceptive deficits significantly predicted eating disorder symptoms 6-months later, while 6-month follow-up interoceptive deficits significantly predicted 12-month follow-up suicidal ideation. Our findings highlight the need for early and regular assessment of suicidal ideation and eating disorder symptoms in adolescents. Given that interoceptive deficits was a shared risk factor for both conditions within this sample, these results underscore the need for targeted interventions aimed at improving interoception.