Older adults are the most sedentary age group, with sedentary behaviour having negative health-related consequences. There is currently limited understanding of how older adults view sedentary behaviour. This study investigated older adults’ understanding of the concept of sedentary behaviour. Semi-structured interviews were conducted with 22 community-dwelling older adults in urban North-West England, selected to be diverse in socio-economic background and activity levels. Interviews were recorded and transcribed verbatim. An inductive thematic analysis was conducted. Participants often construed sedentary behaviour as synonymous with a lack of physical activity, and many perceived reducing sedentary behaviour and increasing moderate-to-vigorous physical activity to be the same thing. Participants perceived the term ‘sedentary’ to have negative connotations and were often judgemental of people who engaged in high levels of sedentary behaviour. Most participants considered reducing sedentary behaviour to be of value, though more active individuals were unconvinced that reducing sedentary behaviour has value beyond the benefits of being physically active. Interventions may wish to provide education to address the misconception that increasing moderate-to-vigorous physical activity is necessary in order to reduce sedentary behaviour. Educating older adults on the independent health consequences of sedentary behaviour may also prove beneficial.