Anxiety disorders (ADs) are the most prevalent comorbidity in Bipolar Disorders (BD), being encountered in up to 75% of cases. In addition to being highly prevalent with BD, ADs and symptoms have a negative impact on almost all aspects of the course and outcome of the illness. Despite our current knowledge about the effectiveness of psychological interventions to treat each condition, the guidelines for the treatment of anxiety disorders comorbid with bipolar disorder (AD-BD) remain unclear. In this chapter, we present an overview of the literature on AD-BD, including an updated systematic review and meta-analysis on the efficacy of psychological interventions for AD-BD (Garceau L, Revue systématique et méta-analyse des interventions psychologiques pour l’anxiété comorbide aux troubles bipolaires [Systematic review and meta-analysis of psychological interventions for comorbid anxiety and bipolar disorders]. Unpublished doctoral dissertation, Université Laval, Québec, 2023; Provencher MD, Garceau L, Fournel I, Lavoie MD, Psychological interventions for anxiety comorbid with bipolar disorder: A systematic review and meta-analysis. In Poster presented at the annual conference of the Association for Behavioral and Cognitive Therapies, 2023). We then present assessment strategies for anxiety symptoms and a treatment approach developed by Steven Jones and colleagues to specifically treat this comorbidity (Jones SH, Knowles D, Tyler E, Holland F, Peters S, Lobban F, Langshaw B, Hilton C, Long R, Gantt K, Owen R, Roberts C, Riste L, Depress Anxiety 35(10):953–965. https://doi.org/10.1002/da.22781, 2018a). The anxiety in context of bipolar disorder (AIBD) development was informed by interviews and focus groups with people with experience of BD and anxiety. Specific CBT strategies included in AIBD draw on relevant best practice guidance from the National Institute for Health and Care Excellence for both ADs and BD. We conclude by highlighting areas that need further research on this highly prevalent comorbidity.