Abstract Background Rhomboid intercostal block (RIB) is a new regional anesthesia technique that provides postoperative analgesia for breast surgery and thoracoscopic surgery. The published papers are not yet fully integrated and do not adequately address the impact and safety of the RIB on postoperative pain. Methods The PubMed, Web of Science and Embase were searched from 2016 to 2021 for all available randomized controlled trials (RCTs) that evaluated the analgesic efficacy and safety of RIB after thoracic surgery and breast surgery. Random and fixed-effects meta-analytical models were used where indicated, and between-study heterogeneity was assessed. The primary outcome was Postoperative Numerical Rating Scale (NRS) scores of patients at rest recorded 0–1, 6–8, 24 h after surgery. The secondary outcomes included rate of postoperative nausea and vomiting (PONV), postoperative fentanyl consumption and presence of complications of the block. Results From 81 records identified, four studies met our inclusion criteria, including 216 patients (RIB:108 patients; no block: 108 patients). In the primary outcome, RIB group showed significantly lower postoperative NRS at rest at first 0–1 h and 6–8 h (weighted mean difference [WMD] = -1.55; 95% confidence internal [CI] = -2.92 to -0.19; p