Background <p>This study aims to synthesise data from randomized controlled trials (RCTs) to evaluate the efficacy and safety of middle meningeal artery embolization (MMAE) in the treatment of nonacute subdural hematoma (SDH).</p> Methods <p>We systematically searched electronic databases for RCTs comparing the efficacy and safety of MMAE with conventional treatment (usual care with or without surgery) for nonacute SDH. The primary efficacy outcome was treatment failure. Secondary efficacy outcomes included changes in hematoma volume, thickness, and functional independence. The primary safety outcome was severe adverse events, and the secondary safety outcome was mortality. Pooled analyses were conducted using risk ratios (RRs) and their 95% confidence intervals (CIs) with random effects model. Trial sequential analysis (TSA) employed to assess the robustness of the evidence.</p> Results <p>Six RCTs with 1481 patients were included in the final analysis. Compared to conventional treatment groups, the proportion of treatment failure were lower in the adjunctive MMAE group (RR 0.48, [95% CI 0.34–0.68]), with TSA suggesting sufficient evidence. There was no significant difference in the risk of severe adverse events between the MMAE and conventional treatment groups (RR 0.85, [95% CI 0.63–1.15]). No significant differences were found in secondary outcomes. Further analysis showed that MMAE plus surgery also significantly reduced the proportion of treatment failure compared to surgery alone (RR 0.55, [95% CI 0.34–0.91]), without increasing severe adverse events. In the TSA, the cumulative z-line crossed the boundary for effect.</p> Conclusions <p>MMAE significantly reduces the risk of treatment failure in patients with nonacute SDH, without increasing the incidence of severe adverse events.</p>