Introduction Promoting physical activity among older adults through sustainable, community-based strategies remains a public health challenge. The ENJOY IMP-ACT project (IMProving older people’s health through physical ACTivity) evaluated a structured implementation framework to increase use of age-friendly outdoor exercise parks across six local government areas in Victoria, Australia. Methods A hybrid type II implementation design was used in a pre-post mixed methods study across six recreational parks. Following a 3-month control phase, the TERM framework (Training, Engagement, Resource development, and Marketing) was implemented over 9 months, with a 3-month maintenance phase. Direct observations assessed park use and activity, and intercept surveys captured health-related behaviours and physical activity levels. Generalised linear models were used to assess changes in park use and physical activity, with regression models adjusting for sociodemographic factors. Results A total of 12,444 visitors were observed, including 1,884 older adults. Park usage by older people increased fourfold post-intervention (IRR 4.03; 95% CI 2.55–6.36), with significant increases in physical activity (IRR 2.03; 95% CI 1.50–2.75). Over 70% of survey respondents met physical activity guidelines post-intervention. Conclusions Implementation of the multi-component framework significantly improved older adults’ engagement in park-based physical activity. The findings highlight that community-based approaches to activate age-friendly outdoor spaces can enhance physical activity opportunities through built environment interventions.