He succeeded his father, Duke Jing, who died in 434 BC.
[1] By the time of Duke You's reign, Jin had already been partitioned into three de facto states: Han, Zhao, and Wei.
The only remaining territories under Jin's control were the capitals, Jiang and Quwo.
While the rulers of Han, Zhao and Wei were nominally vassals of Jin, Duke You had to pay tribute to the former instead.
According to the Records of the Grand Historian, Duke You was killed by bandits when he secretly left the city at night to meet his mistress.