Bipolar disorder (BD) is a chronic, debilitating disorder with recurrent manic and depressive episodes. More than 75% of bipolar patients have a current or lifetime diagnosis of a comorbid anxiety disorder. Comorbid anxiety in BD is associated with greater illness severity, greater functional impairment, and poorer illness-related outcomes. Effectively treating comorbid anxiety in individuals with BD has been recognized as one of the biggest unmet needs in the field of BD. Recently, the Unified Protocol for Transdiagnostic Treatment of Emotional Disorders (UP) was developed to be applicable to the full range of anxiety and mood disorders, based on converging evidence from genetics, cognitive and affective neuroscience, and behavioral research suggesting common, core emotion-related pathology. Here, the authors present a preliminary evaluation of the efficacy of the UP for the treatment of BD with comorbid anxiety, in a clinical replication series consisting of three cases. (Contains 1 table.)