The arrival of Westphalian sovereignty principles in nineteenth-century East Asia was not a uniformly transformative “shock” as commonly assumed. The Sino-centric order did not suddenly disappear; rather it lingered and evolved in a gradual and contested process of change. I argue that enduring domestic understandings of sovereign autonomy affected how Westphalian sovereignty was interpreted in Japan and Korea. Even as the regional structure shifted from regional hierarchy under China to a Western-led international state system, the lens of hierarchy—the long-standing sense of vulnerability and the need to attain autonomous status in a world of great powers—remained unchanged. In addition, each ruling regime in East Asia attempted to reconcile Westphalian sovereignty with existing diplomatic practices to protect its own interests within the Sino-centric order, which resulted in a new hybrid system of interstate relations encompassing notions of both equality and civilizational hierarchy. Within each country, contestation on sovereignty occurred in multiple stages, driven by existing security relationships and changing domestic politics debating the competing standards of civilization in the region.