Parks provide opportunities for physical activity, stress reduction and social interaction and have been shown, in cross-sectional studies, to reduce the likelihood of transition to frailty in older age. We employed a longitudinal design to examine what pattern of residential-based park availability throughout life was associated with frailty transition in later life. Greater childhood distance to neighbourhood parks had consistent associations with declining frailty status in later life (odd ratio per 100 m increase: 1.18, 1.03-1.36). We found that these associations were moderated by socioeconomic factors and the size of the park. Increasing the number and size of child-friendly parks in cities could be an appropriate approach to reduce the burden of frailty in older age.