Background: Given the increasing number of people achieving exceptionally long lifespans, there is an urgent need for a better understanding of mental health in centenarians. This study aimed to understand the prevalence of mental health conditions—depressive symptoms, anxiety, sleep disturbances, disinhibition, and aberrant motor behaviour—among centenarians in Switzerland.

Methods: Data were collected from N = 169 participants via telephone interviews or paper questionnaires, either directly from centenarians or through proxy informants. Half the data were collected during a period when protective measures were imposed due to the COVID‐19 pandemic, and half were collected after the measures were lifted.

Results: Mental health conditions were prevalent in our sample, particularly depressive symptoms (44.51%) and anxiety (42.17%). Significant positive associations were found between depressive symptoms and anxiety, and between disinhibition and aberrant motor behaviour. Furthermore, we identified statistical predictors for the occurrence of mental health conditions. Notably, institutionalised living increased the odds of depressive symptomatology, while those with higher education levels or an absence of cognitive impairment experienced more sleep disturbances. Finally, cognitive impairment was linked to increased disinhibition and aberrant motor behaviour.

Conclusions: The high prevalence of mental health conditions underscores the need for proactive mental health care strategies in advanced old age. Moreover, it is vital to consider the interconnected nature of mental health conditions and to prioritise vulnerable groups, such as centenarians in institutional settings.