Background People with intermittent claudication are significantly less active compared to their peers without intermittent claudication, worsening future health outcomes. Supervised exercise therapy is not commonly available, but behaviour change techniques in unsupervised interventions can improve physical activity. Specific behaviour change techniques, theoretical mechanisms and contextual features linked to effectiveness remain unclear. Objectives To conduct an integrative synthesis of: effectiveness of behaviour change technique-based interventions on daily physical activity and clinical-/patient-reported outcomes; behaviour change techniques and theoretical mechanisms within effective behaviour change technique-based interventions; feasibility and acceptability. Primary outcomes: short term (< 6 months) and maintenance (> 6 months) of daily physical activity. Secondary outcomes: clinical-/patient-reported outcomes. Data sources Seven primary studies databases; Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, Health Technology Assessment Database and Trial Registers to 31 August 2023. Review methods Systematic review 1: interventions incorporating ≥ 1 behaviour change technique (coded using Behaviour Change Technique Taxonomy version 1, and Theoretical Domains Framework). Systematic review 2: quantitative, qualitative, mixed-methods research on patient/provider experiences. Study quality assessed using revised Cochrane risk-of-bias tool for randomised trials; Risk Of Bias In Non-randomised Studies – of Interventions and Mixed Methods Appraisal Tool. Results Fifty-three articles (41 studies) were included in systematic review 1, and 28 articles (28 studies) in systematic review 2. Eleven randomised controlled trials demonstrated that behaviour change technique-based interventions increased daily physical activity in the short term [increase of 0.20 standardised mean difference (95% confidence interval 0.07 to 0.33), ~ 473 steps/day] with high certainty. Evidence of maintenance of daily physical activity is unclear (increase of 0.12 standardised mean difference; ~ 288 steps/day). Behaviour change techniques aimed at improving patients’ intentions to engage in physical activity were most effective. Network analysis suggests that behaviour change technique-based interventions improved daily physical activity and may be better than supervised exercise therapy in maintaining daily physical activity. behaviour change technique-based interventions were acceptable and had short-medium-term benefits to initial/absolute claudication distance/time, walking impairment scores and disease-specific quality of life. Conclusions The behaviour change technique-based interventions are effective, targeting intention to engage in physical activity, in improving daily physical activity and functional outcomes in the short term, although evidence is limited for maintenance. There is a need for more randomised controlled trials examining daily physical activity and clinical outcomes, including longer-term follow-up, with detailed descriptions of behaviour change techniques, costs and provider views. Study registration This study is registered as PROSPERO CRD42020159869. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR130664) and is published in full in Health Technology Assessment; Vol. 29, No. 18. See the NIHR Funding and Awards website for further award information.