Insufficient and unequal access to food (i.e. food insecurity [FI]) has a negative impact on health, especially in vulnerable groups such as adolescents. This study investigates the prevalence of FI and its sociodemographic correlates among adolescents in the Valle de Ricote, Murcia, Spain. Using data from the Eating Healthy and Daily Life Activities (EHDLA) study, a representative sample of 882 adolescents (median = 14, IQR = 2) was analyzed during the 2021–2022 academic year. FI was measured using the Child Food Security Survey Module in Spanish (CFSSM-S). Findings showed a prevalence of FI of 16.2%, with significant sociodemographic disparities. Adolescents from immigrant (odds ratio [OR] = 2.41; 95% CI: 1.38–4.21) and diverse (OR = 2.04; 95% CI: 1.10–3.79) families showed a higher susceptibility to FI. In addition, higher parental education reduced the risk of FI (college education: OR = 0.36; 95% CI: 0.17–0.74). These findings reveal a high prevalence of FI among Spanish adolescents, underscoring the urgent need to implement public health policies and interventions to reduce these social disparities.