Adolescent gadget addiction is an increasing concern alongside the rapid advancement of digital technology. Excessive gadget use may negatively affect physical health, psychological well-being, social interactions, and academic performance. The Family-Based Screen Time Reduction Program is a family nursing intervention that may help address this problem. To describe the implementation of the Family-Based Screen Time Reduction Program in reducing gadget addiction among adolescents through family nursing care. This Final Nursing Scientific Project used a case study design involving three families with adolescents experiencing gadget addiction, selected through purposive sampling. Data were collected through interviews, observations, instrument completion, and documentation using a family nursing assessment form, observation sheets, the Family Gadget Control Card (KKGK), and the Smartphone Addiction Scale–Short Version (SAS-SV). The intervention was conducted over three consecutive days and included education on the impacts of gadget use, development of family media rules, monitoring of gadget use duration, enhancement of parent–adolescent communication, and alternative non-gadget activities. The SAS-SV was administered before and after the intervention, while gadget use duration and compliance with family rules were recorded daily. The intervention improved family knowledge and ability to supervise gadget use, reduced adolescents' screen time, enhanced parent–adolescent communication, and increased participation in family activities without gadgets. The Family-Based Screen Time Reduction Program may be an effective family nursing intervention for reducing gadget addiction among adolescents by strengthening the family's role in supervising and regulating gadget use.