Introduction: Predominant polarity (PP) has emerged as a valuable course specifier in bipolar disorder (BD) with implications for prognosis and treatment planning. As the BD population ages, understanding its clinical characteristics becomes essential to tailor personalized interventions across the lifespan. This study aimed to characterize the distribution and clinical profiles of PP subgroups in a cohort of older adults with BD (OABD). Methods: This cross-sectional study included 101 euthymic OABD aged >50 years. Clinical, neuropsychological and functional characteristics were compared between depressive (DPP), manic (MPP), and undetermined predominant polarity (UPP) subgroups, based on at least 2/3 of lifetime episodes being either depressive or manic polarity. Results: UPP was the most frequent PP in OABD (59.4%), followed by DPP (27.7%) and MPP (12.9%). Patients with DPP presented a later age of onset, a depressive first episode, less psychiatric hospitalizations, and a trend to outperform MPP and UPP in visual memory. Participants with MPP presented more frequently with manic onset. The UPP subgroup exhibited worse clinical outcomes, including higher number of total episodes, more frequent suicidal ideation and seasonality, and worse financial disability compared to DPP. Conclusion: PP classification distinguishes meaningful clinical and cognitive subgroups in OABD. The UPP subgroup associates with greater illness severity and functional impairment. These findings support the integration of PP into personalized treatment and prevention strategies in aging BD. Future longitudinal studies are needed to further clarify the trajectory of PP across the lifespan.