Last June the Holy See had expressed "grave concern" for Peter Shao Zhumin, saying he was being held in an unknown location and had been missing for some time.
His friends said they feared the authorities were trying to force him to switch from the underground church recognised by the Vatican to the state-run Chinese Patriotic Catholic Association (CPCA).
The bishop was released on January 3, Vatican spokesman Greg Burke said.
According to the specialist religious website Asianews.it, Shao had been detained on May 18 after being "invited" to attend an interview with officials of the local Religious Affairs Bureau.
Complicating matters, CPCA clergy chosen by the Communist Party are sometimes accepted by Rome, while Vatican-appointed bishops are not recognised by the government but are sometimes tolerated.
China is estimated to have about 12 million practising Catholics divided between the official and the underground branches of the Church.
Disclaimer: No Business Standard Journalist was involved in creation of this content