Inclusion Criteria:

• Aged 18 to 75 years (inclusive), male or female.
• Diagnosed with ulcerative colitis at least 3 months prior to screening; this diagnosis must be confirmed by endoscopy or histology.
• Patients must have moderate-to-severe active ulcerative colitis, as defined by an mMS score of 4 to 9 (blood in stool subscore ≥ 1, frequency of bowel ovements subscore ≥ 1, and colonoscopy subscore ≥ 2 [as confirmed by the study site's image reviewer]; the sum of these three subscores must be at least 4).
• The investigator determines that the participant has had an inadequate response to or is intolerant of at least one conventional therapy aminosalicylates, corticosteroids, or immunosuppressants) or a biologic agent (anti-TNF-α, anti-α4β7 integrin, or anti-IL-12/23 antibodies, etc.).
• Voluntarily sign the informed consent form and be willing to comply with the study procedures and complete the trial in accordance with the protocol.

Exclusion Criteria:

• Has a diagnosis of Crohn's Disease (CD) or indeterminate colitis (inflammatory bowel disease (IBD)-undefined) or other types of colitis or enteritis that may confound efficacy assessment
• Has a current diagnosis of fulminant colitis and/or toxic megacolon
• Has UC limited to the rectum
• Has a history of or is anticipated to require surgical intervention for ulcerative colitis during the study, including but not limited to ostomy, ileal pouch-anal anastomosis, and intestinal resection.
• Has any active infection as specified in the protocol
• Is known to be infected with hepatitis B virus (HBV), hepatitis C virus (HCV), or human immunodeficiency virus (HIV)
• Has evidence of active tuberculosis (TB) or meets TB exclusionary parameters
• Has a history of cancer (except fully treated nonmelanoma skin cell cancers or cervical carcinoma in situ after complete surgical removal) and is disease free for <5 years before Randomization
• Has had major surgery within 4 weeks before Screening or has a major surgery (ie, surgical procedure requiring general anesthesia) planned during the study
• Has received protocol-specified prohibited medications