After Liu Biao's death in 208, his younger son Liu Cong, who succeeded him, surrendered to Cao Cao when Cao led his forces on a campaign in southern China. Yi Ji joined Liu Bei on a journey southward towards Xiakou (夏口; present-day Wuhan, Hubei), which was guarded by Liu Biao's elder son Liu Qi and was independent of Cao Cao's control. Yi Ji became an official under Liu Bei since then and accompanied him in Yi province. In July 214, after Liu Bei seized control of Yi Province (covering present-day Sichuan and Chongqing) from its governor Liu Zhang, Yi Ji followed Liu Bei to Chengdu, the capital of Yi Province. Liu Bei, who held the nominal appointment of General of the Left () under the Han central government then, appointed Yi Ji as an Assistant Officer of the Household () under him. Liu Bei's treatment of Yi Ji was second to that of Jian Yong, Sun Qian and others.(表卒，遂隨先主南渡江，從入益州。益州旣定，以籍為左將軍從事中郎，見待亞於簡雍、孫乾等。) Sanguozhi vol. 38.
