Purpose <p>This study aimed to assess eating behaviors, dietary habits, and nutritional history in adolescents with pectus excavatum, and to examine the relationships between anthropometric, biochemical, and behavioral variables using multivariate cluster analysis.</p> Methods <p>A total of 25 adolescents (21 males, 4 females) aged 11–18 years with a diagnosis of pectus excavatum participated in this cross-sectional study. Data were collected through sociodemographic surveys, anthropometric measurements, serum ferritin levels, and the Adolescent Eating Behavior Assessment Scale. Cluster analysis was applied to identify patterns between nutritional, anthropometric, biochemical, and behavioral factors.</p> Results <p>Malnutrition was observed in 16% of participants, thinness in 20%, and short stature in 16%. Low serum ferritin levels were found in 20% of the cohort. Nutritional problems were reported by 72% of adolescents, mainly appetite loss (55.6%) and food neophobia (44.4%). Only 44% had been breastfed up to two years, and the majority (96%) exhibited moderate eating behaviors. Cluster analysis revealed two main clusters linking nutritional and behavioral variables with biochemical status and lifestyle factors.</p> Conclusion <p>This study is the first to highlight the relationship between eating behaviors, breastfeeding duration, and daily meal frequency in adolescents with pectus excavatum. The findings emphasize the importance of early nutritional assessment and tailored interventions to support growth and overall health in this population.</p>