He was initially created the Duke of Fucheng and was said to be intelligent from his youth, and he and his older brother Yuwen Yong (by another concubine, Lady Chinu) studied the Shi Jing and the Zuo Zhuan together.
In 553, Western Wei seized the modern Sichuan and Chongqing region from the Liang Dynasty pretender Xiao Ji.
Yuwen Tai responded, "A provincial governor needs to pacify the people and rule over them, and you are too young to do that.
Yuwen Xian, despite his young age of 15, was said to be a capable governor, paying attention to the people's concerns and to the important matters and making good decisions on legal cases.
In winter 564, when Yuwen Hu, in alliance with Tujue, launched a major attack on rival Northern Qi, Yuwen Xian was sent to command part of the army attacking Luoyang, along with Yuchi Jiong, Daxi Wu (達奚武), and Wang Xiong (王雄).
Around the new year 570, Yuwen Xian was sent to try to capture the Northern Qi city of Yiyang (宜陽), near Luoyang, and while he was not successful against Hulü, the armies stalemated.
In winter 570, Hulü changed tactics and headed north, encroaching onto Northern Zhou territory north of the Fen River (汾水, flowing through modern Linfen, Shanxi) and seizing substantial amount of territory.
Emperor Wu comforted him and had him take over Yuwen Hu's post of Da Zhongzhai (大冢宰) -- but reduced the power of the post from being prime minister to only being minister of palace affairs, therefore reducing Yuwen Xian's authority while ostensibly promoting him.
Emperor Wu personally attacked Luoyang, but after sieging it for 20 days without capturing it, he grew ill and was forced to withdraw.
In winter 576, Emperor Wu again attacked Northern Qi, with Yuwen Xian as one of his major generals.
The attack, while initially repelled by Northern Qi, was very successful, and Yuwen Xian greatly contributed to the eventual seizure, around new year 577, of Northern Qi's secondary capital Jinyang (晉陽, in modern Taiyuan, Shanxi).
Yuwen Xian's army was said to be so disciplined that the people of Northern Qi were barely disturbed by them.
In 578, Emperor Wu was launching a campaign against Tujue, but Yuwen Xian, apprehensive of his own successes on the battlefield, declined a commission from Emperor Wu to lead the army, making an excuse that he had a skin disorder that made it difficult for him to attend to the army.
Emperor Xuan, who was erratic in his behavior, greatly suspected Yuwen Xian on account of his ability.