This research examines physical activity (PA) parameters among urban-living middle-aged and older Japanese during the Tokyo Olympic build-up period. Population sampling was employed, and an online survey was administered with 4,000 adults across Japan’s five largest cities. The International Physical Activity Questionnaire-Short Form constituted the main outcome variable, with auxiliary measures of Olympic interest and engagement, readiness for PA behavior change, perceived environmental barriers, and demographic information. Despite interest in the Olympics (>60% moderate–high interest), planned engagement with the event was low (>70% planned passive engagement). Higher levels of interest and planned engagement were both significantly correlated with greater self-reported PA participation (p < .001). Across the sample, the PA levels were in the low–moderate range (990 metabolic equivalent of task-min/week), with significant variations observed by the age-cohort and geographic area (p < .001). Age-cohort and geographic variations were also identified with regard to readiness for PA behavior change and perceived environmental barriers to activity (p < .001). Older age (65 years and above) and host city (Tokyo) residence emerged as correlates of higher levels of PA, greater readiness for behavior change, and fewer reported barriers to participation. These findings have implications for Olympic legacy management and successful transitions from middle age to later life in Japan.