Teacher work engagement is central to sustaining educational quality and teacher well-being, yet prior studies have largely overlooked individual heterogeneity and developmental change. This study applied a person-centered, longitudinal design to identify engagement profiles, examine transitions, and explore predictors and outcomes among Chinese teachers. Drawing on the Job Demands-Resources (JD-R) model, we focused on perceived organizational support (POS) as a contextual resource, teacher professional identity (TPI) as a personal resource, and job burnout as an outcome. Data were collected from 1,018 teachers across kindergarten, primary, junior high, and senior high schools at two waves over 39 months. Work engagement was measured via vigor, dedication, and absorption; POS and TPI at Time 1; and burnout at Time 2. Latent Profile Analysis and Latent Transition Analysis were conducted. Three profiles emerged consistently at both time points: Low Dedication Engagement, Moderate Engagement, and High Engagement. Dedication was the most discriminative dimension, underscoring its cultural salience in the Chinese teaching context. While profiles showed structural stability, many teachers transitioned upward: nearly one-third of the Low Dedication group moved to higher engagement, and 30% of the Moderate group advanced to High Engagement. Regression analyses indicated that POS predicted upward shifts from Low Dedication to High Engagement, whereas TPI predicted transitions from Moderate to High Engagement. Both resources reduced risks of downward movement. Engagement profiles were strongly linked to burnout: highly engaged teachers reported the lowest levels, while those in the Low Dedication group reported the highest. These results demonstrate that engagement protects against stress and resource depletion. Overall, this study highlights the dynamic and culturally embedded nature of teacher engagement and suggests differentiated strategies, enhancing organizational support for disengaged teachers and strengthening professional identity for moderately engaged teachers, to sustain well-being and educational quality.