Background: Although low levels of physical activity have slightly decreased globally, the need to reverse the physical inactivity remains urgent. One approach has been the installation of outdoor gyms (OGs). Method: A natural experiment arose from the installation of OGs in different neighborhoods of the city of Temuco, Chile. Baseline measurements were collected between 2006 and 2017 in a cohort of adults participating in the Prospective Urban & Rural Epidemiology study. Physical activity was assessed with the short version of the International Physical Activity Questionnaire, and time-varying covariates was assessed every 3 years. The multistage hierarchical, nested sampling process and the follow-up assessments led to data correlated at different levels, thus the authors analyzed the data using a logistic multilevel model. Result: 2463 urban adults from 16 neighborhoods, with an average age of 51.7 (9.8) years (67% female), were included. Having an adequate number of OGs improved the odds of complying with the World Health Organization’s recommendations (adjusted odds ratio = 4.64, 3.95–5.45). In addition, being male (odds ratio = 1.53, 1.32–1.77) and under the age of 60 years (odds ratio = 0.83, 0.71–0.97) were associated with being physically active. Conclusion: The presence of more OGs can have a positive impact on physical activity recommendations.