Objectives: Older adults with bipolar disorder (OABD) are vulnerable for a COVID-19 infection via multiple pathways. It is essential for OABD to adhere to the COVID-19 measures, with potential consequences for the psychiatric symptoms. This situation offers the unique opportunity to investigate factors of vulnerability and resilience that are associated with psychiatric symptoms in OABD. Methods: This study included 81 OABD patients aged over 50 years. Factors measured at baseline in patients that participated in 2017/2018 were compared with factors measured during the COVID-19 outbreak. Results: Participants experienced less psychiatric symptoms during COVID-19 than (67.9% euthymic) than at baseline (40.7% euthymic). There was no difference in loneliness between COVID-19 and baseline. Not having children, more feelings of loneliness, lower mastery, passive coping style and neuroticism were associated with more psychiatric symptoms during COVID-19 measures. Conclusions: Participants experienced less psychiatric symptoms during COVID-19 measures when compared to baseline. Our results indicate promising targets for psychological interventions aimed at curing and preventing recurrence in OABD and improving quality of life in this growing vulnerable group.