After settling the nearby provinces, including a rebellion led by former Yellow Turbans, and internal affairs with the court, Cao Cao turned his attention north to Yuan Shao, who himself had eliminated his northern rival Gongsun Zan that same year. Yuan Shao, himself of higher nobility than Cao Cao, amassed a large army and camped along the northern bank of the Yellow River.

In 200, after winning a decisive battle against Liu Biao at Sha County and putting down the rebellions of Xu Gong and others, Sun Ce was struck by an arrow and fatally wounded. On his deathbed, he named his younger brother, Sun Quan, as his heir.

Following months of planning, Cao Cao and Yuan Shao clashed at the Battle of Guandu. Overcoming Yuan Shao's superior numbers, Cao Cao decisively defeated him by setting fire to his supplies, and in doing so crippled the northern army. Liu Bei fled to join Liu Biao in Jing Province, and many of Yuan Shao's forces were destroyed. In 202, Cao Cao took advantage of Yuan Shao's death and the resulting division among his sons to advance north of the Yellow River. He captured Ye in 204 and occupied the provinces of Ji, Bing, Qing and You. By the end of 207, after a lightning campaign against the Wuhuan barbarians, Cao Cao had achieved undisputed dominance of the North China Plain.