Wu Kaifeng, a member of the Standing Committee of the municipal party committee and secretary-general of Wenzhou in Zhejiang Province, received the punishment for violating party discipline.
A post on China's Twitter-like Sina Weibo detailing Wu's extramarital relationship with a woman went viral at the end of March.
The party's disciplinary watchdog will investigate the case, they said.
He is one of several officials who faced such allegations in the recent past.