Problematic internet use and unsafe internet use are the two main potential negative consequences of children's online activities. Parents play a vital role in mitigating these consequences and creating a safe digital environment. Parental Vigilant Care (PVC) is a systematic approach that integrates active and restrictive mediation practices, allowing parents to regulate their involvement according to the alarm signs they detect. This study is a randomized controlled trial designed to assess the efficacy of the PVC parent training program. Families were randomly assigned to either the three-session PVC group (n = 92) or the control group (n = 65). Measures from parents and children (77% male; 12-16 years old) were assessed at baseline, postintervention, and an 8-week follow-up. In addition to self-report questionnaires, children's online activities (time and content) on smartphones were monitored. Compared to the control group, parents in the PVC group reported a lower sense of helplessness, fewer conflicts, improved child functioning, a better family climate, and greater knowledge of their children's online activities. Additionally, children demonstrated lower scores for problematic and unsafe internet use. A gradual reduction in children's time online and use of unsafe sites was observed during the intervention following the PVC training. Guided by the PVC model, parents increased their protective presence in their children's digital world, thereby reducing online risks for their children. (PsycInfo Database Record (c) 2025 APA, all rights reserved).