A Study of Guselkumab in Participants With Active Psoriatic Arthritis

Prior treatment

• Has previously received any biologic treatment
• Has ever received tofacitinib, baricitinib, filgotinib, peficitinib, decernotinib, upadacitinib or any other Janus kinase (JAK) inhibitor
• Has received any systemic immunosuppressants (example, azathioprine, cyclosporine, 6 thioguanine, mercaptopurine, mycophenolate mofetil, hydroxyurea, tacrolimus) within 4 weeks of the first administration of study intervention

Other illness

• Has known allergies, hypersensitivity, or intolerance to study intervention or its excipients
• Has other inflammatory diseases that might confound the evaluations of benefit of guselkumab therapy, including but not limited to rheumatoid arthritis (RA), axial spondyloarthritis (AS)/non-radiographic axial spondyloarthritis (nr-axSpA), systemic lupus erythematosus, or Lyme disease

• Have active psoriatic arthritis (PsA) despite previous non-biologic disease-modifying antirheumatic drug (DMARD), apremilast, and/or nonsteroidal anti-inflammatory drug (NSAID) therapy
• Have a diagnosis of PsA for at least 6 months before the first administration of study agent and meet Classification criteria for Psoriatic Arthritis (CASPAR) at screening
• Have active PsA as defined by: at least 3 swollen joints and 3 tender joints at screening and at baseline; and C-reactive protein (CRP) greater than or equal to (\>=) 0.3 milligrams per deciliter (mg/dL) at screening from the central laboratory
• Have \>= 2 joints with erosions on baseline radiographs of the hands and feet as determined by central read
• Have at least one of the following PsA subsets: distal interphalangeal joint involvement, polyarticular arthritis with absence of rheumatoid nodules, arthritis mutilans, asymmetric peripheral arthritis, or spondylitis with peripheral arthritis
• Have active plaque psoriasis, with at least one psoriatic plaque of \>= 2 centimeter (cm) diameter or nail changes consistent with psoriasis