BACKGROUND: Globally, 10% of children and adolescents live with mental health problems and often lack high-quality care. Over 80% of people facing mental health issues reside in low- and middle-income countries (LMICs). Failing to address children's mental health may prolong these challenges into adulthood, impeding their chances for a healthy life. This scoping review aims to describe the types, implementation strategies, effectiveness, and gaps of existing interventions for preventing and treating mental health problems in early childhood (<10 years) in LMICs. METHODS: The study employed a scoping review of experimental studies published 2007-2023. Major databases including PubMed, Embase, Web of Science, and PsycINFO were searched using key terms related to the population (children), intervention (mental and/or behavioural health programmes), and outcome (mental health problems). Three authors independently conducted search strategy, article screening, data extraction, and quality assessment. The findings were presented using descriptive analysis and narrative synthesis. RESULTS: Of 39 499 identified articles, 33 were included in the study, covering 7629 children and published between 2009-2022. Seventeen studies (51.5%) were from upper-middle-income countries, 13 (39.4%) were from lower-middle-income, and three (9.1%) were from low-income countries. Enrolment was community-based in 23 studies and health-facility based in 10 studies; the majority (79%) focused on children aged 3-8 years old. Almost two-third (63.6%) of studies were conducted in urban settings. Programmes encompassed various interventions such as parenting programmes (33.3%). A majority of studies (57.5%) employed group therapy for delivering the programme, with mental health professionals (21.2%) acting as the primary intervention providers. Interventions were primarily received by children (39.4%), followed by mothers/caregivers (33.3%). Most studies explored disruptive disorders (20 studies), social and behavioural problems (16 studies), and anxiety disorders (12 studies). Statistically significant intervention effects on child mental health outcomes were reported for 90% of published studies. CONCLUSIONS: Diverse behavioural programmes that improve the mental health of young children are available and effective in LMICs. Most interventions were delivered in urban settings and focus was on the use of health care professionals. Diverse intervention approaches, including parenting programmes and group therapy, were effective in addressing various mental health issues among young children.