Sarcopenia is characterized by progressive loss of muscle mass, strength, and physical performance, yet current diagnostic tools are limited for practical and longitudinal monitoring. To explore alternative biomarkers, we performed quantitative proteomic profiling of plasma-derived extracellular vesicles (EVs) in the community-based Korean Frailty and Aging Cohort Study (KFACS). Longitudinal analysis revealed that EV-associated complement proteins, particularly C2 and C4B, were strongly associated with declines in gait speed and elevated in individuals with worsened outcomes over two years. Complement pathway enrichment and associations with inflammatory and aging-related signatures underscored their biological relevance. Independent validation in the hospital-based OsteoSarcopenia cohort at Seoul National University Bundang Hospital confirmed the predictive value of C2 and C1R for gait speed and SPPB decline, with AUC values exceeding 0.7. for clinically relevant measures. These findings position EV-derived complement proteins as promising circulating biomarkers for sarcopenia progression and offer insight into their broader role in aging-related processes.