The legality of euthanasia and assisted suicide (AS) and nature of regulations of these practices remain controversial and the subject of lively debate among experts and the general public. Our study investigates attitudes and behaviours towards AS among older adults in Switzerland where the practice of AS has a relatively long history and remains rather unregulated. We aim to explore how individuals' preferences regarding their end of life, as well as individuals' trust in institutions involved in the practice or control of AS are associated with attitudes and behaviours towards AS. We analyse nationally representative data of adults aged 55 and over from wave 6 (2015) of the Survey of Health, Ageing and Retirement in Europe (SHARE) in Switzerland (n = 2,145). While large majorities supported current legal arrangements around AS in Switzerland (81.7%) and stated that they could consider AS for themselves under certain circumstances (61.0%), only a minority either was a member of a right-to-die organisation already (4.9%) or stated they were likely to become a member of such an organisation (28.2%). Stated preferences for control over the end of life and for maintaining essential capabilities at the end of life showed a positive association with AS-related attitudes and behaviours, whereas preferences for feeling socially and spiritually connected, as well as for not being a burden displayed a negative association with our outcomes. Higher levels of trust in one's relative were positively associated with both support for the legality of AS and potential use of AS. A positive association was also found between trust in the Swiss legal system and support for the legality of AS. By contrast, trust in religious institutions displayed a negative association with all five AS-related attitudes and behaviours. Similarly, trust in healthcare insurance companies was negatively associated with potential use of AS. Taken together, older adults were generally supportive towards current practices regarding AS. This approval appears to be closely related to individuals' preferences and, at different extends, to trust in social and public institutions with regard to end-of-life issues, which is relatively high in Switzerland.