He came to prominence as a general under the Prince of Donghai, Sima Yue, after he quelled the rebellions of Gongshi Fan (公師藩), Ji Sang and Shi Le.
Because of this, former generals of Ying led by Gongshi Fan rebelled in the region, attacking many local counties and commanderies before making their way to Yecheng.
In 306, Gou Xi’s army killed Gongshi Fan while he and his soldiers were trying to cross the Yellow River from Baima (白馬; near present-day Hua County, Henan).
Gou Xi and Ji Sang and Shi Le's forces were locked in a stalemate for several months at Pingyuan and Yangping (陽平; in present-day Shen County, Shandong) while Sima Yue provided Gou Xi with support from Guandu (官渡; northeast of present-day Zhongmu County, Henan).
The pair decided to flee to Liu Yuan's state of Han-Zhao, but were forced to split up after they were intercepted and routed by Ding Shao (丁紹) along the way.
Gou Xi's feats in defeating Gongshi Fan, Ji Sang and Shi Le made him highly revered by the populace of his time.
As reward for quelling the rebellions, Sima Yue made Gou Xi General Who Nurtures The Army and Chief Controller in Qingzhou and Yanzhou.
However, their relationship began to crack when, at the advice of Pan Tao (潘滔), Sima Yue appointed himself the Governor and acting Chief Controller of Yanzhou while moving Gou Xi to positions in Qingzhou.
[9] When Gou Xi arrived in Qingzhou to assume his posts, he immediately implemented excessively strict laws and oversaw many executions each day, earning him the nickname 'Butcher (屠伯)'.
In 307, the Administrator of Dunqiu (頓丘, in present-day Qingfeng County, Henan) Wei Zhi (魏植), rebelled in Yanzhou, but was quickly defeated by Gou Xi.
[12] Emperor Huai's first edict to him was to put down Wang Mi and his subordinate Cao Ni, who were now generals of Han-Zhao, as they were threatening the Luoyang region again.
Pan Tao escaped, but his colleagues Liu Zeng (劉曾) and Cheng Yan (程延) were executed by Gou Xi.
Gou Xi wrote a petition to the emperor asking him to move the capital over to Cangyuan (倉垣, in present-day Kaifeng, Henan) in Yanzhou.
Luoyang was in a dire situation at this point due to an ongoing famine and the Han-Zhao threat, but Emperor Huai faced a number of difficulties in trying to leave the capital.