We conducted a scoping review to provide the most recent evidence of the resources (legal, financial, human, infrastructural) allocated to child and adolescent mental health (CAMH) and the effectiveness of CAMH interventions in 15 low- and middle-income countries of the region. Data were gathered from peer-reviewed publications and grey literature in both English and local language published since 2016, yielding a total of 16,869 publications in the initial search, including 15,708 peer-reviewed studies and 1161 grey literature publications, of which 260 English publications (118 peer-reviewed and 142 grey literature) and 384 local languages publications (124 peer-reviewed and 260 grey literature publications) were included in the review. China had the most included articles (53.7%), whereas the Pacific Island Countries (PICs), aside from Papua New Guinea, had the least. Legislation and policies on CAMH are underdeveloped in most PICs. Information on CAMH spending was available only in China, where 0.04% of total health spending was allocated to curative care for adolescent mental health. Countries with available data spent 1% or less of their total health spending on mental health overall (including CAMH), with CAMH beds ranging from 1.83% to 4.19% of total mental health beds and CAMH psychiatrists ranging from 0 to 34.2 per 100,000. Service utilization was low: children and adolescents made up 1.5%–5.4% of all mental health admissions. Effectiveness studies were found in only four countries: China, Malaysia, the Philippines, and Viet Nam. The review highlights significant knowledge gaps and challenges in CAMH resources in the WPR's LMICs, underscoring the need for stronger political commitment, financial investment, multisectoral collaboration, service delivery capacity, and research efforts. Given the predominance of evidence from China compared to other LMICs, this paper focuses on the latter, with China discussed in a separate paper in this Series.