OBJECTIVES: To evaluate the efficacy of low-intensity pulsed ultrasound (LIPUS) in orthodontic tooth movement (OTM) and orthodontically induced root resorption (OIRR) across animal and human studies. MATERIALS AND METHODS: An electronic search in MEDLINE, Embase, Web of Science, Cochrane Library, National Knowledge Infrastructure, and Wanfang Database up to May 2024 identified 931 records screened using predefined PICOS criteria. 18 animal and 8 human studies met the inclusion criteria, with 12 suitable for meta-analysis. Methodological qualities for animal studies were assessed using the SYRCLE tool and ARRIVE guidelines. For clinical trials, the Cochrane RoB 2.0 tool and ROBINS-I were applied to evaluate the risk of bias in randomized clinical trials (RCTs) and controlled clinical trials (CCTs), respectively. Evidence quality was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and quantitative analysis employed RevMan software with an inverse variance method and random effects models for all included studies. RESULTS: Most animal and human studies had a high or unclear risk of bias. LIPUS significantly accelerated OTM in rats, showing increases of 0.08 mm (95% CI, 0.02 to 0.13; P = 0.006), 0.11 mm (95% CI, 0.04 to 0.17; P = 0.001), and 0.11 mm (95% CI, 0.06 to 0.16; P < 0.0001) on days 5, 7, and 14. In clinical trials, LIPUS reduced treatment duration with clear aligners by 352.07 days (95% CI, -524.81 to -179.34; P < 0.0001), but had no significant effect on OIRR (P > 0.05). GRADE analysis indicated very low evidence quality for both outcomes. CONCLUSIONS: LIPUS may accelerate OTM but shows weak evidence for alleviating OIRR. More well-designed studies with standardized methodology are needed. CLINICAL RELEVANCE: LIPUS could benefit OTM acceleration, but its effect on OIRR remains inconclusive.