Nomophobia refers to an intense anxiety and stress caused by being out of contact with mobile phones (MPs). It is known that excessive engagement with MPs decreases adolescents' psychological well-being, social and academic functioning. The aim of this study was to investigate the associations of nomophobia with alexithymia which is characterized by difficulties in describing and expressing emotions and using empathy, and with the metacognition characteristics which have the function of controlling the cognitions in an adolescent population. The study was conducted on 1817 participants (n = 972, 54% female, n = 835, 46% male). The Nomophobia Questionnaire (NMP-Q), The Twenty-Item Toronto Alexithymia Scale (TAS-20) and The Metacognition Questionnaire for Children and Adolescents (MCQ-C) were administered to participants. A question form for socio-demographic data was also administered to participants and their families. Cathegorical variables were analyzed by chi-square test, and numerical variables were analyzed by independent sample t test. The relationships between the scales' scores were analyzed by the Pearson-product moments correlation test. The predictive effects of alexithymia, metacognition problems and gender were assessed by multiple linear regression analysis. Nomophobia, alexithymia and metacognition problem levels were significantly higher in females than males. There was a significant correlation between NMP-Q and TAS-20 scores and MCQ-C scores. TAS-20, MCQ-C scores and gender significantly predicted the nomophobia when NMP-Q score was a dependent variable. Therapeutic interventions for improving social skills like emphatic thinking and/or increasing emotional expression may be beneficial in the treatment of adolescents with alexithymic traits which experience nomophobia. Moreover, interventions that enhance metacognitive skills which can control negative thoughts triggered by the possibility of losing contact with MPs may increase treatment success.