Objective: No synthesis of the Australian evidence regarding targeted prevention and early intervention for mental health concerns among young children exists. This review aimed to (1) describe the types of targeted community-based mental health programmes evaluated in Australia to support children aged 1–9 years exhibiting internalising and/or externalising symptoms and (2) examine their impact on children’s internalising and externalising symptoms and disorder diagnosis. Method: A systematic review and meta-analysis was conducted (PROSPERO: CRD42021255257). Four databases (PsycINFO, PsycArticles, MEDLINE and CINAHL) were searched for Australian studies published in the past 10 years that quantitatively evaluated the impact of a targeted programme on children’s mental health. The National Institute of Health Quality Assessment Tools were used to evaluate the study quality. Results: Forty-two studies were included; the majority (67%) were medium quality. The mean sample size was 142 (SD = 170), children’s average age was 5.78 years (SD = 2.44) and 58% were male. Aboriginal and Torres Strait Islander children were underrepresented. Studies evaluated 16 programmes that targeted (1) externalising symptoms ( n = 20 studies, n = 6 programmes), (2) internalising symptoms ( n = 14 studies, n = 7 programmes) or (3) both, termed transdiagnostic programmes ( n = 8 studies, n = 3 programmes). Externalising programmes achieved a significant moderate mean reduction in externalising behaviours (standardised mean differences = −0.56), internalising programmes yielded a small mean improvement in anxiety symptoms (standardised mean differences = −0.25) and 57% reduced odds of anxiety disorder diagnosis. Evidence supporting transdiagnostic programmes was inconclusive. Conclusion: Parenting-focused programmes targeting young children’s internalising or externalising behaviours have the largest local evidence base supporting their effectiveness. Limitations include a lack of engagement with fathers, triangulation of outcomes, homogeneity and implementation reporting. Greater implementation and evaluation of community-driven integrated and systemic approaches that identify, engage and support Australia’s most disadvantaged cohorts of young children and their families are needed.