Background: The transformation of Internet use into some disruptive patterns of behavior and cognitions results in Pathological Internet Use (Davis, 2002). For this reason, individuals' cognition about Internet use gains importance. Metacognition and personality are frequently used concepts to explain the nature of psychopathology. The aim of this study is to investigate the effects of personality characteristics, metacognition and Internet usage functions on non-functional cognitions related to Internet usage in university students. Methods: 687 Turkish university students (521 girls, 164 boys and 2 other and aged mean 20.13) is participated. The Big Five Inventory (BFI: Benet-Martu0131u00b4nez & John, 1998), Metacognitions Questionnaire-30 (MCQ-30; Wells & Cartwright-Hatton, 2004), Internet Use Function Questionnaire (IUFQ; Ju, 2000), Online Cognition Scale (OCS; Davis, Flett & Besser, 2002) and a demographic form were used in this study.Findings: Regression analysis results showed that the non-functional cognitions related to Internet usage were significantly predicted by personality traits, metacognition and Internet usage functions. In addition, metacognition has a fully mediated role in the predictive effect of personality on non-functional cognitions related to Internet usage.Discussion: The non-functional cognitions related to Internet usage was found to be correlated with some personality dimensions (eg. Neuroticism) (Durak & u015eenol-Durak, 2014). In the present study, the relationship between personality and the non-functional cognitions related to Internet usage is mediated by metacognition. It is stated that the reason for this situation may be negative metacognitions which can not be controlled and contain dangerous thoughts with positive metacognitions including behaviors related to control of thought and emotion (Casale, Caplan & Fioravanti, 2016; Spada, Caselli, Nikcevic & Wells, 2015). It has been found that all dimensions of metacognition predicted Pathological Internet Use (Spada, Langston, Nikcevic & Moneta, 2008). The Internet usage functions (social, leisure and virtual) were important for the Pathological Internet Use (Bozou011flan, Demirer & u015eahin, 2014; Ceyhan, 2010).