The rapid urbanization of the Klang Valley, Malaysia, has led to increased provision of Outdoor Fitness Equipment (OFE) in urban parks to support active living and community well-being. Despite their proliferation, existing OFE installations often lack a systematic design framework that integrates user perception, usability, and freetime considerations. This study, situated within a Design and Development Research (DDR) methodology, aims to propose a comprehensive design framework that enhances OFE usability for middle-aged urban park users. Using a mixed-methods approach involving surveys with 270 respondents, observational studies, and expert interviews, data were triangulated to identify the key determinants of OFE engagement. Findings indicate that perception (ease of understanding, safety, attractiveness), usability (ergonomics, instructional support, inclusivity), and freetime (time allocation, accessibility, motivational triggers) significantly shape user engagement and long-term adoption. The proposed Design Framework for Outdoor Fitness Equipment (DFOFE) synthesizes these factors into practical guidelines for product design planners, offering evidence-based recommendations for inclusive, safe, and sustainable OFE in Malaysian urban parks. This study contributes to knowledge by extending human-centered and inclusive design theories into the under-researched domain of public fitness infrastructure and offers practical insights for designers, urban planners, and policymakers seeking to foster healthier urban communities.