In his youth, Li Jiongxiu passed the imperial examinations and was made an officer at Xiang Prefecture (相州, in modern Handan, Hebei).
Li Jiongxiu himself had married a wife of high birth, Lady Cui, but Lady Cui was in the habit of using harsh language against her female servants—which, when Li Jiongxiu's mother heard, hurt her badly as they reminded her of her own sufferings as a servant.
In 701, while still serving as minister of defense, Li was given the designation Tong Fengge Luantai Pingzhangshi (同鳳閣鸞臺平章事), making him a chancellor de facto.
Initially, on account of Li Jiongxiu's association with the Zhangs, he was further demoted to be the secretary general at Heng Prefecture (near modern Hengyang in Hunan).
Emperor Zhongzong died suddenly in 705—a death that traditional historians believed to be a poisoning carried out by his wife Empress Wei and daughter Li Guo'er the Princess Anle.
Li Jiongxiu's responsibilities during the initial stages of Emperor Ruizong's reign were unclear, but it appeared that he was at one point commissioned to command an army either intending to attack or to defend against an attack from Eastern Tujue, and upon his return from that mission, after the chancellor Yao Chong, who was serving as minister of defense as well, was removed in 711, Li Jiongxiu became minister of defense again, but not chancellor.