He was renowned for pacifying the Guanzhong region, which had been seized by agrarian rebel generals Moqi Chounu (万俟醜奴) and Wang Qingyun (王慶雲) in 530.
In 528, when Erzhu Rong set out to destroy the rebel Emperor of Qi, Ge Rong (葛榮), he entrusted his entire home base, including Bing Province (并州, roughly modern Taiyuan, Shanxi) to Erzhu Tianguang as well, remarking, "Only you can make me feel secure about places where I am not at."
After Yuan Hao's defeat, Emperor Xiaozhuang created Erzhu Tianguang the greater title of Duke of Guangzong.
However, Heba Yue declined to be in command, believing that he would draw suspicions even if were victorious, and instead offering to serve under a member of the Erzhu clan.
Erzhu Tianguang was given a relatively small army, and initially the campaign against Moqi appeared hopeless, but with Erzhu Tianguang himself and Heba both being capable generals, they scored initial victories and then misled Moqi into believing that they would rest several months before taking further action.
Late in 530, Emperor Xiaozhuang, apprehensive that Erzhu Rong would eventually seized the throne, ambushed him in the palace and killed him.
Both Emperor Xiaozhuang and Yuan Ye conferred princely titles on Erzhu Tianguang, and Erzhu Tianguang eventually accepted Yuan Ye's bestowment of the Prince of Longxi title, but did not make further threatening gestures against Emperor Xiaozhuang.
However, when the general Gao Huan rebelled at Xindu (信都, in modern Hengshui, Hebei) later in the summer, Erzhu Tianguang abandoned his planned campaigns against the rebel generals Gedouling Yili (紇豆陵伊利) and Moqi Shouluogan (万俟受洛干), who controlled the modern central and western Gansu, and prepared for possible action in the east, although he did not immediately intervene in the campaign between Gao and his fellow Erzhu clan members, even after Gao defeated Erzhu Zhao in battle late in 531.