Inclusion Criteria:
1. Male or female participants aged 18 to 75 years (inclusive) at the time of signing the informed consent form (ICF)
2. Diagnosis of chronic spontaneous urticaria (CSU) for ≥6 months before the screening visit, with persistent itch and hives despite treatment with H1-antihistamines (H1-AHs) for ≥6 weeks within the year before screening.
3. During the 7 days before randomization, participants must have a 7-Day Urticaria Activity Score (UAS7) ≥16 and a 7-Day Itch Severity Score (ISS7) ≥8, with an in-clinic Urticaria Activity Score (UAS) ≥4 at least one of the screening visit days or at randomization visit.
4. Participants must be willing and able to complete a daily symptom electronic diary (eDiary) as required by the protocol throughout the study.
5. Female participants must not be pregnant or breastfeeding. Participants and their partners must agree to use the contraceptive methods from the time of signing the informed consent form throughout the treatment period and for the period specified in the protocol after the last administration of the investigational product. Participants and their partners must also refrain from donating sperm or ova during this period.
Exclusion Criteria:
1. History or current presence of inducible urticaria with a clearly identifiable trigger, or any other condition that may present with symptoms of urticaria and/or angioedema.
2. Participants with any chronic pruritic skin disease other than CSU that may interfere with the evaluation of the study results.
3. Participants with chronic hepatitis B, chronic hepatitis C, syphilis, or human immunodeficiency virus (HIV) infection.
4. Active tuberculosis or autoimmune disease; known or suspected immunodeficiency; or a history of unusually frequent, recurrent, or prolonged infections, as determined by the investigator.
5. History of vernal keratoconjunctivitis (VKC) and/or atopic keratoconjunctivitis (AKC) within 6 months before screening.
6. History of an inadequate response to biologic therapy for CSU, or prior treatment with an interleukin-4 (IL-4), interleukin-13 (IL-13), interleukin-4 receptor (IL-4R), or interleukin-33 (IL-33)/suppression of tumorigenicity 2 (ST2) inhibitor.
7. Prior treatment with a biologic agent without completion of the applicable washout period specified in the protocol before screening.
8. Use of immunosuppressive or immunomodulatory medications within 30 days or 5 half-lives before screening, whichever is longer.
9. Use of topical corticosteroids for the treatment of CSU, or oral doxepin, within 14 days before screening.
10. Use of traditional Chinese medicines, including herbal or proprietary Chinese medicines intended to treat CSU, or receipt of phototherapy within 30 days before screening.
11. Any other known systemic disease or laboratory abnormality that, in the investigator's judgment, may make the participant unsuitable for participation in the study.
