Inclusion Criteria:
* Participant with a diagnosis of chronic plaque psoriasis (PsO) with or without psoriatic arthritis, for at least 6 months prior to Baseline.
* Stable moderate chronic plaque psoriasis at both Screening and Baseline as defined as:
* Body Surface Area (BSA) ≥ 10% and ≤ 15%,
* Psoriasis Area and Severity Index (PASI) ≥ 12, and
* Static Physician Global Assessment (sPGA) = 3 (moderate) based on a 5-point scale (0 to 4).
* Participant must be a candidate for systemic therapy as assessed by the investigator
* Psoriasis inadequately controlled by topicals, phototherapy and/or systemic treatments (including, but not limited to, methotrexate, apremilast, cyclosporine A, corticosteroids, and/or cyclophosphamide)
Exclusion Criteria:
* Participants with any form of PsO other than chronic plaque PsO (e.g., pustular PsO, palmoplantar pustulosis, acrodermatitis of Hallopeau, erythrodermic, or guttate PsO).
* Participants with a history of current drug-induced PsO or a drug-induced exacerbation of preexisting PsO.
* Participants with a history of active ongoing inflammatory skin diseases other than PsO (with or without PsA) that could interfere with the assessment of PsO (e.g., hyperkeratotic eczema).
* Participants with a history of severe renal insufficiency defined as creatinine clearance \< 30 mL/min and/or requiring hemodialysis or peritoneal dialysis.
* Participantswith a history of clinically significant (per investigator's judgment) drug or alcohol abuse within the last 6 months.
* Participants with a history of an allergic reaction or significant sensitivity to constituents of the study drugs (and its excipients) and/or other products in the same class.
* Participants who have had major surgery performed within 12 weeks prior to randomization or planned during the conduct of the study (e.g., hip replacement, aneurysm removal, stomach ligation).
* Participants with evidence of:
Hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, defined as:
* HBV: Hepatitis B surface antigen (HBs Ag) positive (+) test or detected sensitivity on the HBV DNA PCR qualitative test for subjects who are hepatitis B core antibody (HBc Ab) positive (+) (and for hepatitis B surface antibody \[HBs Ab\] positive \[+\] participants where mandated by local requirements).
* HCV: HCV RNA detectable in any participant with anti-HCV antibody (HCV Ab).
* Human immunodeficiency virus (HIV), defined as confirmed positive anti-HIV Ab test and considered to have unstable disease (Unless meeting criteria for stable disease) Participants with HIV with no history of AIDS-defining conditions AND stable disease for at least 6 months prior to screening can be enrolled. Criteria for stable disease is achieved if all below criteria are met. Documentation of "stable disease" can be done at the Screening visit or by documentation of labs performed within 1 month of the Randomization visit, in addition to the subject's medical history.
* On stable antiretroviral therapy;
* Viral load (HIV RNA) below the lower limit of quantification by a validated and approved plasma HIV-1 RNA quantitative assay;
* CD4+ T cell count ≥ 500 cells/μL.
\- Participants with any of the following medical diseases or disorders:
* Recent (within past 6 months) cerebrovascular accident or myocardial infarction;
* History of an organ transplant which requires continued immunosuppression;
* Active or suspected malignancy or history of any malignancy within the last 5 years except for successfully treated non-melanoma skin cancer (NMSC) or localized carcinoma in situ of the cervix.
* Prior history of suicide attempt at any time in the subject's lifetime prior to signing the informed consent and randomization, or major depression or suicidal ideation or attempt requiring hospitalization within the last 3 years prior to signing the informed consent.
* Hereditary problems of galactose intolerance, total lactase deficiency, or glucose-galactose malabsorption.
\- Participants who received within 30 days prior to Baseline any:
* Other systemic immunomodulating treatments (including, but not limited to:
e.g., methotrexate, apremilast, cyclosporine A, corticosteroids, cyclophosphamide, tofacitinib \[Xeljanz®\]);
* Other systemic PsO treatments (e.g., retinoids, fumarates, any other drug known to possibly benefit PsO);
* Photochemotherapy (e.g., PUVA), phototherapy (e.g., UVB) or prolonged exposure or use of tanning booths or ultraviolet light sources.
* Participants who received within 14 days prior to Baseline any topical treatment for PsO or any other skin condition (including, but not limited to: e.g., corticosteroids, vitamin D analogues, vitamin A analogues, pimecrolimus, retinoids, salicyl vaseline, salicylic acid, lactic acid, tacrolimus, tar, urea, or anthralin).
* Participants who have been treated with any strong cytochrome P450 enzyme inducers (e.g., rifampin, phenobarbital, carbamazepine, phenytoin, St. John's Wort) within 30 days or 5 half-lives of start of treatment with deucravacitinib.
* Participants who received any live viral or bacterial vaccine within 4 weeks prior to the first dose of study drug, or expect the need for live vaccination during study participation including at least 147 days (21 weeks or as guided by the local risankizumab label \[if approved\], whichever is longer) after the last dose of risankizumab or at least 30 days after the last dose of deucravacitinib.
* Participants who have been treated with any investigational drug within 30 days or 5 half-lives of the drug (whichever is longer) prior to the first dose of study drug or be currently enrolled in another interventional clinical study.
