Summary Background Omalizumab is approved as an add‐on therapy for the treatment of chronic spontaneous urticaria (CSU) in patients with inadequate response to H1‐antihistamine treatment. The urticaria control test (UCT) is a reliable, concise tool developed as an alternative to the 7‐day urticaria activity score (UAS7) – the standard for CSU disease activity assessment. Objectives This prospective, open‐label, phase IV study evaluated the efficacy and safety of omalizumab in French adult patients with CSU nonresponsive to H1‐antihistamine treatment. Materials and methods Patients n = 136; stratified 1 : 2 (with angio‐oedema : without angioedema) received omalizumab 300 mg subcutaneously every 4 weeks for 12 weeks. Study assessments included UCT, UAS7, angio‐oedema activity score and d‐dimer levels (exploratory objective). Results At Week 12, 74·6% of the patients achieved disease control UCT score ≥ 12 (primary endpoint) and 67·7% of patients showed well‐controlled disease (UAS7 ≤ 6). There was a strong negative correlation between UCT score and UAS7 at Week 12 (Spearman's correlation coefficient −0·839). Mean plasma d‐dimer concentration was elevated at baseline (1002·1 ng mL−1) and decreased notably at Week 8 (455 ng mL−1). Among the nine patients with a very high baseline d‐dimer concentration (> 3000 ng mL−1), eight were responders (UAS7 ≤ 6) at Week 12. Conclusions Omalizumab was efficacious in patients with CSU nonresponsive to H1‐antihistamines. The UCT was a reliable tool for disease assessment and the scores correlated well with UAS7. This study does not support the usefulness of d‐dimer to monitor long‐term disease prognosis in adult urticaria; however, it may indicate patients who respond to omalizumab. What's already known about this topic? Omalizumab is recommended as the third‐line treatment for chronic spontaneous urticaria (CSU), as an add‐on to H1‐antihistamines. The urticaria control test (UCT) is a recently validated tool for disease control assessment in patients with CSU. Elevated plasma levels of d‐dimer observed in some patients with CSU suggests a potential role of d‐dimer as a biomarker in CSU treatment response and prognosis. What does this study add? Omalizumab controlled symptoms and improved quality of life in French patients with moderate‐to‐severe CSU. UCT was a reliable tool for the assessment of urticaria control. d‐dimers are elevated in some patients with CSU and change in response to treatment with omalizumab. This study does not support the usefulness of d‐dimer to monitor long‐term disease prognosis in adult urticaria; however, it may indicate patients who respond to omalizumab. Linked Comment: Giménez‐Arnau. Br J Dermatol 2019; 180:12–13. Plain language summary available online Respond to this article