The increasing availability and prevalence of the internet among children and adolescents are becoming a growing challenge for families and parents, particularly in the form of managing the child’s use to avoid problematic internet use by the child. Problematic internet use is increasingly present in society, especially among children and adolescents, but there is still no accepted definition of this construct among researchers. In this paper, problematic internet use is operationalized using the generalized problematic internet use model, which includes four interrelated components: preference for online social interaction, use of the internet for mood regulation, deficient self-regulation, and negative outcomes (Caplan, 2010). Adolescents are arguably the most vulnerable age group for developing problematic use (Carbonell et al., 2012; Kaltiala-Heino et al., 2004), as they use the internet more than any other age group (Anderson et al., 2017). Previous research (e.g., Bleakley et al., 2016; Warren & Aloia, 2019) has shown that parental interventions such as parental mediation can prevent problematic internet use. Parental mediation refers to how parents enable and mediate the child’s use of and access to digital technologies (Clark, 2011). The strategies most used by parents are active mediation, restrictive mediation, parental monitoring, and technical mediation (Livingstone et al., 2017). However, some studies have shown that some strategies, such as restrictive mediation, can increase compulsive internet use (Azeveda et al., 2020). The inconsistency of previous findings was the impetus for establishing a model to examine the moderating effects of parental mediation on relationships within Caplan’s (2010) model of generalized problematic internet use. Thus, this research aimed to examine the relationship between parental mediation and problematic internet use among early adolescents. Four research questions were posed: 1) to empirically test the model of generalized problematic internet use; 2) to examine the relation between parental mediation strategies and the components of generalized problematic internet use among adolescents; 3) to examine the relation between parental education and internet skills with the components of generalized problematic internet use among adolescents and parental mediation strategies; and 4) to examine how parental mediation strategies alter the relation among the components of generalized problematic internet use among adolescents within the model of generalized problematic internet use. Method This research study consisted of a pilot study and a main study. The pilot study was conducted in two parts: 1) live with 280 children aged 10 to 15 years and one of their parents; and 2) online with 141 parents of children aged 10 to 18 years. The pilot study was conducted to check the psychometric characteristics of the translated instruments and the newly constructed Parental Mediation Scale. The participants of the main study were 342 children aged 10 to 15 years and one of their parents. To examine parental mediation, the Parental Mediation Scale, developed for the study and reviewed in the pilot study, was used, and completed by both parents and children. Children’s problematic internet use was measured using the Generalized Problematic Internet Use Scale 2 (Caplan, 2010). Parental internet skills were also measured using the Internet Skills Scale (van Deursen et al., 2016) and adolescent self-regulation was measured using the Adolescent Self-Regulation Scale (Moilanen, 2007). The statistical processing of the results included principal component analysis, confirmatory factor analysis, correlational analysis, structural equation modelling, and moderating effects analysis. Results Empirical testing of the generalized problematic internet use model showed that the model fit the data well, and three of four direct effects and two of three indirect effects in the model were confirmed. The multigroup analysis showed that the conclusions about the fit of the model to the data drawn based on the whole sample apply equally to boys and girls, younger and older, those who use a cell phone for two or fewer hours per day and those who use it for more than two hours, and those who have specific rules for smartphone use and those who do not. Results show that more frequent use of restrictive mediation by parents, as rated by themselves and by adolescents, and more frequent use of active mediation, as rated by adolescents, were associated with lower preference for online social interactions among adolescents. Those adolescents who rated more frequent parental use of restrictive mediation and monitoring had higher ratings of negative outcomes, while frequent parental monitoring rated by youth was shown to be associated with higher generalized problematic internet use. Parental education showed no significant associations with the components or total score of generalized problematic internet use. Adolescents whose parents rated their internet skills higher, used the internet more for mood regulation. In the case of parents with higher education, children estimated that their parents used active parental mediation more often. Parents with higher education reported less frequent use of restrictive mediation. Parents who rated their internet skills higher according to the adolescents’ and their own responses were also more likely to use active mediation, while they were more likely to use technical mediation only according to their own ratings. The results also show how the frequency of parental control use can alter the relationship between decreased self-regulation and negative outcomes in the generalized problematic internet use model. Results show that for children who do not have self-regulation problems, more frequent parental monitoring may increase negative outcomes, whereas for children with self-regulation problems, more frequent use of parental monitoring may decrease negative outcomes caused by internet use. Conclusion The study contributed to a better understanding of the effects of parental mediation, i.e., parental monitoring, on the association between decreased self-regulation and negative outcomes in children during early adolescence. Knowledge of the effects of parental behaviour on the negative outcomes of children’s internet use can be used to develop science-based prevention interventions and counselling programs aimed at preventing problematic internet use among adolescents.