Introduction The impact of adding leukotriene receptor antagonists (LTRAs) to antihistamines for chronic urticaria (CU) is unclear, leading to a lack of definitive guidance. We systematically reviewed and meta-analyzed the use of add-on LTRAs for CU. Methods For the 2024 AAAAI/ACAAI JTFPP CU guidelines, we searched MEDLINE, Embase, CENTRAL, ICTRP, CBM, CNKI, VIP, and Wanfang to March 12, 2023 for randomized controlled trials (RCTs) evaluating combination LTRA plus antihistamines versus antihistamines alone for CU. We performed random effects meta-analyses addressing urticaria (combination of itch and hives; UAS7; 0–42; lower better), itch, and hive severity (both NRS; 0–3; lower better), quality of life (QoL; DLQI; 0–30; lower better), and adverse events (AEs). The GRADE approach determined certainty of evidence. Results We identified 3,364 citations and ultimately included 33 RCTs representing 3,168 participants (mean age: 36.2 years). 32 RCTs addressed montelukast and 1 addressed zafirlukast. High certainty evidence shows that add-on LTRAs reduce urticaria (mean difference [MD]: -5.17, 95%CI -6.53 to -3.80), itch (MD: -0.25, 95%CI -0.39 to -0.10), and hive (MD: -0.25, 95%CI -0.41 to -0.08) severity. Low certainty evidence suggests that add-on LTRAs may improve QoL (MD: -4.40, 95%CI -8.15 to -0.65). AEs (relative risk: 0.80, 95%CI 0.56 to 1.15, moderate certainty) probably have little to no difference between groups. No RCT addressed neuropsychiatric AEs. Conclusion Compared to antihistamines alone, combination LTRAs plus antihistamines modestly reduce urticaria severity, may improve QoL and probably do not increase overall AEs in patients with CU. These findings support optimal CU management and updated guidelines.