Background: Promoting physical activity among older adults is essential for extending healthy life expectancy. Municipality-led walking programs have been introduced in Japan; however, evidence of their effectiveness in promoting readiness for lifestyle improvement among older adults remains limited. We examined the association between participation in a municipality-led walking promotion program and readiness for lifestyle improvement among community-dwelling older adults. Methods: Data of community-dwelling adults aged ≥65 years who participated in a municipality-led walking promotion program implemented in Zushi City, Japan, in 2021, were compared with those of non-participants selected from the National Health Insurance database. Behavioral readiness was evaluated using the five-stage classification of the transtheoretical model. Pre- and post-intervention stages were assessed in both groups. Associations between participation and behavioral stage were examined using ordinal logistic regression with unadjusted, basic-adjusted, and fully adjusted models, controlling for baseline stage and habitual exercise. Results: Participants in the walking event had higher odds of being at a higher readiness stage than non-participants (unadjusted odds ratio [OR]=2.91; basic-adjusted OR=2.99; fully adjusted OR=2.98). Analyses using a dichotomized transtheoretical model variable also indicated consistently higher odds of being in the action or maintenance stages among participants. Conclusion Our findings suggest that short-term, municipality-led walking initiatives contribute to early-stage behavioral readiness for lifestyle improvement in older adults. They provide a valuable foundation for planning community-based health promotion and long-term care prevention strategies. Further studies are needed to evaluate similar programs across different settings and over more extended periods.