Biologic disease-modifying antirheumatic drugs (bDMARDs) are engineered proteins with high affinity for various proinflammatory immune mediators to reduce inflammation and its sequelae in various rheumatic diseases. These medications, introduced at the advent of the 21st century, have revolutionized the treatment of axial spondyloarthritis (including ankylosing spondylitis) and psoriatic arthritis. Currently approved bDMARDs for axial spondyloarthritis are etanercept, infliximab, adalimumab, golimumab, certolizumab pegol, and secukinumab. For psoriatic arthritis, all of these drugs are approved in addition to ixekizumab, ustekinumab, abatacept, and tofacitinib. Selection of the optimal bDMARD should consider patient comorbidity including uveitis, psoriasis, and inflammatory bowel disease.