For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit www.BMSStudyConnect.com Inclusion Criteria: - Active ulcerative colitis (UC) extending ≥ 15 cm from the anal verge and confirmed by a screening/baseline colonoscopy/sigmoidoscopy prior to the randomization visit - Documented diagnosis of UC of at least 3 months' duration prior to screening - Must have active moderate to severe UC, as defined by a modified Mayo score of 5 to 9 points, inclusive, which includes a stool frequency (SF) subscore of ≥ 2, and a rectal bleeding (RB) subscore ≥ 1, and a screening endoscopic (ES) subscore of ≥ 2 - Documentation of an inadequate response, loss of response, or intolerance to at least one of the medications including Oral 5-aminosalicylic acids (5-ASAs) (eg, mesalamine, sulfasalazine, olsalazine, or balsalazide), CS such as Corticosteroids (eg, prednisone ([or equivalent)] or budesonide ([or equivalent)]), Immunosuppressants such as Immunomodulators (eg, azathioprine ([AZA),], 6-mercaptopurine ([6-MP),], or methotrexate ([MTX)]), Anti-tumor necrosis factor-alpha (TNF)--α) agents (eg, infliximab, adalimumab, or golimumab), Integrin inhibitor (eg, vedolizumab), Anti-interleukin (IL)-12/IL-23p40 antibodies (eg, ustekinumab) - Males and females must agree to follow specific methods of contraception, if applicable Exclusion Criteria: - Current or recent (within 12 weeks prior to the randomization visit) evidence of fulminant colitis, abdominal abscess, toxic megacolon, or bowel perforation - History or evidence of any extensive colonic resection, subtotal or total colectomy, with or without presence of a stoma or ileoanal pouch - Current or recent (within 3 months before the first dose) gastrointestinal disease, including gastrointestinal surgery, which could impact the absorption of study treatment, or current or recent (within 6 months before the first dose) gastrointestinal resections - Women who are pregnant or breastfeeding Other protocol-defined inclusion/exclusion criteria apply