The present study was conducted to investigate the effectiveness of treatment based on mentalization on cognitive fusion and psychological resilience of divorced adolescents with internalized behavioral-emotional disorder. The current study was a semi-experimental application with a pre-test-post-test design with a control group and a two-month follow-up period. The statistical population of the present study was made up of divorced adolescents suffering from internalized behavioral-emotional disorder in the first and second period of secondary education in Asadabad city, Hamadan province in 2022-2023. In this research, 35 adolescent were selected by purposeful sampling and randomly assigned to experimental and control groups (18 adolescent in the experimental group and 17 adolescent in the control group). The adolescent in the experimental group received the treatment based on mentalization during eight weeks in eight 90-minute sessions. Children and Adolescents Behavioral Inventory (CABI), Cognitive Fusion Questionnaire (CFQ) and Psychological Resilience Questionnaire (PRQ) were used in the present study. The data were analyzed through mixed ANOVA via SPSS23 software. The results showed that treatment based on mentalization has significant effect on the cognitive fusion (p<0001) and psychological resilience (p<0001) in the divorced adolescents with internalized behavioral-emotional disorder.