Background: Fundamental movement skill (FMS) competence is associated with physical activity during childhood, with higher FMS competence associated with higher physical activity levels; however, the effectiveness of FMS interventions in primary school-aged children is not fully understood. Objective: The purpose of this study was to evaluate the effectiveness of FMS interventions at improving daily levels of moderate to vigorous physical activity (MVPA) in 5- to 11-year-old children. Methods: Systematic searches were completed in eight electronic databases (MEDLINE, CINAHL, PubMed, Web of Science, SPORTDiscus, EMBASE, ERIC and Scopus). Studies were included if they were randomised or non-randomised controlled trials that implemented a physical activity intervention with an FMS component in 5- to 11-year-old children and included objectively measured daily levels of MVPA. Methodological quality was assessed using the Cochrane risk of bias tools for randomised and non-randomised controlled trials. Random effects meta-analysis was performed to determine the pooled intervention effect (mean difference) on minutes spent in MVPA with meta-regression for the use of an operationalised definition of FMS, in line with the criteria reported by Logan et al. Results: A total of 19 studies were identified for review and 14 studies were eligible for meta-analysis. The pooled intervention effect was 4.3 min (95% confidence interval [CI] − 0.03 to 8.8) of MVPA per day. The percentage of future studies likely to find an effect greater than the minimal clinically important difference was 47% (95% CI 22–70). Studies that attempted to conceptualise and define FMS by combining at least one of Logan and colleagues’ operational definitions with a measure of FMS had a positive effect on daily MVPA (13.3 min/day, 95% CI 8.0–18.6; R 2 = 0.89). Meta-regression for the three levels of criteria reported by Logan et al. showed a linear increase in MVPA, with studies using all three criteria experiencing the largest additive effect (15.7 min/day, 95% CI 8.9–22.6; R 2 = 0.89). Conclusions: FMS interventions have the potential to increase daily levels of MVPA in 5- to 11-year-old children. However, future studies should concentrate on establishing an accurate conceptualisation of FMS and how FMS will be integrated within their intervention to further increase physical activity levels. Trial Registration: Prospero registration number: CRD42017058718.