Omalizumab is a humanized anti-IgE, which is indicated for managing chronic spontaneous urticaria (CSU). The dynamic change trend of the efficacy of omalizumab for CSU is unclear. We searched Cochrane, OVID, Embase, Web of Science, and ClinicalTrials.gov for randomized controlled trials (RCTs) of omalizumab versus placebo in CSU patients from inception to January 2023. The primary outcome was the percentage of complete responders (defined as the weekly urticaria activity score as 0, UAS7 = 0). Secondary outcomes were the percentage of participants with UAS7 ≤ 6, the percentage of weekly itch severity score minimally necessary difference responders (defined as a reduction from baseline in ISS7 of ≥ 5 points, ISS7 MID), and adverse events (AEs). 12 randomized, placebo-controlled studies with 2166 patients with CSU were included. Compared with the placebo, the omalizumab group significantly improved UAS7 = 0, UAS7 ≤ 6, and the percentage of ISS7 MID responders. Over the order of publication time, drug dose, and sample size increased, the efficacy had become more stable and accurate. It was recommended to increase studies with high quality and large samples and to reduce blind repetitive RCTs to avoid wasting scientific and medical resources.