Face prototype formation plays a pivotal role in translating face experience into robust internal representations. However, the early developmental trajectory and experiential influences on this cognitive capacity remain underexplored. Across five within-subject experiments conducted in Canada and China across different time periods, we investigated how face race and environmental context modulate infant prototype formation. Using a novel prototype formation paradigm, we discovered infants consistently exhibited stronger prototype formation for unfamiliar other-race faces compared to own-race faces, and this bias increased significantly with age. Furthermore, we demonstrated remarkable plasticity. Infant cohorts tested during and after COVID-19 lockdowns show opposite age-related trajectories in face prototyping, reflecting differential environmental exposure to diverse faces. These findings illuminate the experience-dependent nature of early face processing specialization, suggesting infants’ prototype formation dynamically adapts to optimize face processing within specific environments. We discuss implications for understanding the developmental origins of face processing biases and potential social consequences.