Background <p>There is limited literature on emotional regulation and cognitive control in adolescent patients with bipolar disorder (BD) in response to positive emotional stimuli. Few brain functional magnetic resonance imaging (fMRI) studies have employed emotion-based Go/No-Go tasks to examine neural process underlying BD. This study aimed to investigate alterations of brain activity on fMRI during positive emotional stimuli (i.e., happy faces) and its impact on attentional processing in adolescent patients with BD.</p> Method <p>This study enrolled 43 adolescents diagnosed with BD and 18 age- and gender-matched healthy controls. All participants underwent structured interviews, questionnaire/scale assessment for BD symptoms, and task-based brain fMRI with an emotional Go/No-Go paradigm. Clinical data and neural activity in response to neutral and positive emotional stimuli were compared between the groups.</p> Results <p>Compared to the healthy controls, the patients with BD showed significantly increased activity in key regions within the cognitive control network, the default mode network, and the limbic system under the “happy-Go minus neutral-Go” condition during the brain fMRI. Notably, hyperactivation in the left dorsolateral superior frontal gyrus, left opercular part of the inferior frontal gyrus, left inferior parietal lobule, and left thalamus was significantly correlated with the emotional Go omission rate.</p> Conclusion <p>This study showed alteration of brain activity in specific brain regions for attentional control and emotional regulation in adolescents with BD during positive emotional stimuli. The results of this study enhance our understanding of neurobiological mechanisms underlying adolescent BD and implicate potential treatment strategies focusing on attentional training and emotional management.</p>