BACKGROUND Physical inactivity is a risk factor for many noncommunicable diseases. As reported by the World Health Organisation, 81% of children worldwide are physically inactive. Environmental factors, such as neighbourhood walkability, can shape people's physical activity (PA) behaviour. This study explored the association between neighbourhood walkability and after-school PA among Australian schoolchildren. METHODS The Department for Education and Child Development (DECD) distributed the survey to 189 schools across South Australia to assess the health and well-being of schoolchildren aged between 8 and 14 years. Neighbourhood was defined as an area corresponding to a four digit postcode, and its walkability was measured using Walk Score® . The association between neighbourhood walkability and after-school PA was analysed using multinomial logistic regression adjusted for age, gender, SEIFA score, number of days of TV watching, number of times of eating junk food, neighbourhood safety and children's weight status. RESULTS Children residing in highly walkable areas (walker's paradise) compared to car-dependent areas had higher odds (OR(95%CI)) of engaging in after-school PA three (1.216 (1.029, 1.436), P = .021), four (1.287 (1.064, 1.557), P = .009) and five times a week (1.230 (1.030, 1.133), P = .022) compared to children never participating in PA. CONCLUSIONS Living in highly walkable areas (walker's paradise), compared to living in car-dependent areas was associated with higher levels of after-school PA. So what? Creating walkable neighbourhoods with greater access to amenities, services and public transportation may help increase after-school PA among schoolchildren.