OBJECTIVES: This study explored the experiences and acceptability of a novel, home-based, walking exercise behaviour-change intervention (MOtivating Structured walking Activity in people with Intermittent Claudication (MOSAIC)) in adults with Peripheral Arterial Disease (PAD). DESIGN AND SETTING: Individual semi-structured audio-recorded interviews were conducted with adults with Peripheral Arterial Disease who had completed the MOSAIC intervention as part of a randomised clinical trial. Data were analysed using inductive reflexive thematic analysis and interpreted using the seven-construct theoretical framework of acceptability of healthcare interventions (TFA). PARTICIPANTS: Twenty participants (mean age (range) 67(54-80) years, 70% male, 55% White British) were interviewed. RESULTS: One central theme was identified: Acceptability of walking exercise as a treatment. This theme was explained by four linked themes: Exploring walking exercise with a knowledgeable professional, Building confidence with each step, Towards self-management-learning strategies to continue walking and The impact of walking exercise. These themes were interpreted using six of the seven TFA constructs: affective attitude, burden, perceived effectiveness, intervention coherence, opportunity costs, and self-efficacy. CONCLUSIONS: Participants perceived MOSAIC as an effective, acceptable, and low burden intervention. Physiotherapists were regarded as knowledgeable and supportive professionals who helped participants understand PAD and walking exercise as a treatment. Participants developed confidence to self-manage their condition and their symptoms. As participants confidence and walking capacity improved, they expanded their activities and gained a more positive outlook on their future. MOSAIC is an acceptable intervention that may facilitate adoption of and access to exercise for people with PAD.