The environments in which young and middle-aged adults live may influence their physical activity (PA) behaviours. These associations are less clear among older adults. We estimated cross-sectional and prospective associations of population density, junction density, and land use mix and perceived active living environments with accelerometer-assessed PA in a cohort of older adults. Adults living in more dense and mixed neighbourhoods had less optimal activity profiles at baseline and less optimal changes in activity. Better perceptions were associated with more overall PA at baseline. Interventions for older adults may wish to target individuals living in more dense and mixed neighbourhoods.