An important consideration for determining the severity of mental health symptoms is their impact on youth’s daily lives. Those wishing to assess ‘life impact’ face several challenges: First, various measurement instruments are available, including of global functioning, health-related quality of life and well-being. Existing reviews have tended to focus on one of these domains; consequently, a comprehensive overview is lacking. Second, the extent to which such instruments truly capture distinct concepts is unclear. Third, many available scales conflate symptoms and their impact, thus undermining much needed analyses of associations between the two. A scoping umbrella review will examine existing reviews of life impact measures for use with children and youth aged 6–24 years in the context of mental health and well-being research. We will systematically search six bibliographic databases (MEDLINE, Embase, APA PsycINFO, CINAHL, Web of Science, and the COSMIN database of systematic reviews of outcome measurement instruments), and conduct systematic record screening, data extraction and charting based on methodological guidance by the Joanna Briggs Institute. Data synthesis will involve the tabulation of scale characteristics, feasibility and measurement properties, and the use of summary statistics to synthesise how these instruments operationalise life impact. The protocol was registered prospectively with the Open Science Framework (osf.io/ers48).