He defended Fancheng (凡城, in modern Kazuo County, Liaoning) from Later Zhao in 339 and helped defeat Ran Min with Yao Xiang and Shi Zhi during the Yan-Wei War in 351.
Following his conquest of Yan in 370, Former Qin's ruler, Fu Jian, lamented that he was unable to recruit Yue Wan while he was still alive.
Yue Wan was of Xianbei ethnicity and began his career in Yan as the City Chief of Kehu (榼盧城; east of present-day Funing District, Hebei) before becoming a part of Murong Huang's personal staff as one of his marshals.
Murong Huang appointed Yue Wan as General Who Resists Difficulties and sent him to defend the city with 1,000 soldiers.
Surrounded, Ran Min suffered a great defeat and barely escaped back to Yecheng with a few remaining riders.
Ran Wei was eventually conquered by Yan in 352, and later that year, Murong Jun would declare himself Emperor, signifying his independence from the Jin dynasty.
In 354, Yue Wan followed Murong Ke to Lukou (魯口; in present-day Raoyang County, Hebei) to subdue the self-proclaimed King of Anguo, Lü Hu.
After more than a hundred fortified places surrendered to Yan, Yue Wan was appointed Inspector of Bingzhou to settle the people in the province.
Yue Wan had grown to the position of Left Supervisor of the Masters of Writing and was bestowed the title of Duke of Guangxin.
Realizing this growing issue, in 368, Yue Wan said to Murong Wei, "The balance of power now lies in three states, with each side seeking to swallow the other.
Though they greatly benefitted the state, Yue Wan became feared and despised by court officials who bore the brunt of his reforms.
Qin's ruler, Fu Jian, heard of Yue Wan's services after his conquest and became regretful with the fact that he was unable to meet him.
In a passage said by Murong De's official, Han Zhuo (韓卓), in regard to rectifying the household register, it reads, "...if I then met with the punishment of Shang Yang or the fate of Yue Wan, I would utter no complaint.