Background <p>Evidence on dietary patterns and incident sarcopenic obesity (SO) remains limited, and whether associations vary by baseline body composition status is unclear. This study aimed to investigate associations between dietary patterns and incident SO and examine potential effect modification by baseline status (normal, obesity only, or sarcopenia only).</p> Methods <p>This study included 3,398 community-dwelling Chinese older adults free of SO at baseline. Dietary data was assessed using a 280-item validated quantitative food frequency questionnaire (FFQ); a priori dietary indices (Diet Quality Index-International [DQI-I], Mediterranean-DASH Intervention for Neurodegenerative Delay [MIND], Okinawa diet score, and Dietary Inflammatory Index [DII]) were calculated, and <i>a posteriori</i> dietary patterns were derived using factor analysis. SO was defined as the coexistence of sarcopenia (Asian Working Group for Sarcopenia 2025 criteria) and obesity (based on body fat percentage). Cox proportional hazards models were used to estimate hazard ratios (HRs) for incident SO.</p> Results <p>During four years of follow-up, 266 participants developed SO, with approximately 80% of incident cases occurring among participants with baseline obesity. Higher DQI-I (HR 0.854, 95% CI 0.756–0.964 per SD increase), MIND (HR 0.853, 95% CI 0.754–0.965), and Okinawa (HR 0.866, 95% CI 0.764–0.982) scores were associated with a lower risk of incident SO, whereas higher DII scores increased incident SO risk (HR 1.158, 95% CI 1.007–1.332). In stratified analyses, associations for antioxidant-rich (higher MIND and Okinawa scores) and pro-inflammatory (higher DII) diets were significant only among participants with baseline obesity, with no significant associations in those with normal body composition or sarcopenia only.</p> Conclusions <p>Adherence to dietary patterns with low inflammatory potential and high antioxidant capacity may mitigate the progression from obesity to SO in older adults.</p>