Circadian rhythms, the body’s internal clock, are essential for regulating mood, sleep, and energy levels. Disruptions in these rhythms are linked to the occurrence and recurrence of mood episodes in bipolar disorder, acting as both risk markers and prodromal symptoms for the disorder. Individuals with the disorder often exhibit evening chronotypes, heightened sensitivity to circadian misalignment, and mood episodes tied to these disruptions. Research highlights specific genetic factors, such as variations in clock genes, and the impact of environmental cues, or zeitgebers, in aligning internal rhythms with external cycles. Additionally, serotonin and melatonin play critical roles in mood stability. Advances in digital phenotyping and actigraphy found differences in activity, social and sleep–wake patterns between bipolar patients and healthy controls, even during euthymic periods, as well as among bipolar patients across mood states. Effective management of bipolar disorder involves psychosocial interventions such as interpersonal and social rhythm therapy (IPSRT) and cognitive behavioral therapy for insomnia in bipolar disorder (CBTI-BD), light-based therapies, and pharmacological treatments like lithium and melatonin agonists. Regularly monitoring circadian rhythms using tools like the Pittsburgh Sleep Quality Index (PSQI) and the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) is crucial for the early detection of circadian dysfunctions. Emphasizing circadian regulation in bipolar management improves patient outcomes, with future research aiming to develop personalized treatment strategies based on individual circadian profiles.