New parents are less likely to be active and are more likely to be lonely. Both physical inactivity and loneliness pose public health issues as they are linked with poor physical and mental health outcomes. Parents with perinatal mental illness may face additional barriers to group walking such as anxieties about socialising and leaving the house. This evaluation explores the feasibility and impact of a postnatal walking group set up with perinatal mental health services in Sheffield. Outcomes included reducing social isolation, increased confidence and more access to peer support.