Objectives <p>Qualitative data about the experiences of family carers of people with intellectual and developmental disabilities participating in online mindfulness-based interventions are limited. We aimed to understand the perceived impacts of an online mindfulness programme for family carers of people with intellectual and developmental disabilities.</p> Methods <p>Twenty-seven family carers (16 mothers, four fathers, five adult sisters, two adult brothers) of children and adults with intellectual and developmental disabilities were interviewed about their participation in an online mindfulness programme delivered with/without peer mentor telephone support. Interviews were recorded, transcribed verbatim, and data were analysed using reflexive thematic analysis.</p> Results <p>Family carers were not always able to embed mindfulness practices in their lives, but adapted their learning to their needs, using mindfulness as a flexible tool. Perceived direct benefits included improved wellbeing and greater acceptance. Perceived indirect benefits to family and improved relationships were also described. A valued outcome for siblings was the acceptance of their caring role, whereas parents were more focussed on strategies to improve everyday lives.</p> Conclusions <p>Differences in the way that mindfulness is approached may exist between sibling and parent carers, indicating that sibling experiences should be considered independently of other family carers in future research. These findings directly inform the planning of mindfulness support for families in practice.</p>