In recent years there have been growing concerns about problematic Internet use (PIU) as potential mental health problem. Among the many activities available on the Internet, the time spent gaming appears one of the most frequent risk factors in developing PIU. The aim of the current study was to model the relationship between negative affect, metacognitions about online gaming, frequency of online gaming and PIU. A total of 326 Italian gamers (mean age = 27 years, SD = 5.65 years; 93.3% males) participated in the study. The pattern of relationships specified by the theoretical model was examined through path analysis. Results showed that negative affect was directly associated with all other variables. Specifically, positive, strong and direct associations were found between negative affect and both positive and negative metacognitions about online gaming. Moreover, negative metacognitions about online gaming were strongly linked to PIU. Overall, the theoretical model was supported showing that metacognitions about online gaming may play a role in the association between time spent on online gaming to a broader pattern of PIU. Results are discussed within the context of the metacognitive model of psychopathology and clinical implications based on this model are outlined.