Peripheral Arterial Disease (PAD) is a chronic cardiovascular disease. It is highly prevalent in older adults. Mobile Health (mHealth) and Telehealth technologies are considered two central digital solutions for enabling patient-centred care. There is evidence that physical activity apps can improve health outcomes in adults. The aim of this project is to develop a prototype of smart phone app to target patients with PAD, which we named YORwalK, to promote exercise and track changes in walking ability in this population. We used a multidisciplinary team combined with a User Centred Design approach. We performed an evaluation survey using modified System Usability Scale (SUS). The survey was to assess the usability of the App and completed by health care professionals. The App was developed based on the concept of promoting behaviour change through feedback and life style prompts. YORwalK features incorporate self-monitoring and motivating feedback. SUS result indicating higher usability of the App.