Ji Jianye was found to have "received a huge amount of money and gifts either by himself or through his family members", the Central Commission for Discipline Inspection (CCDI) said in a statement posted on its website.
It added that the former mayor was deemed "morally corrupt".
Ji -- who earned the nickname "Bulldozer Ji" for his promotion of construction projects in the city of eight million -- was sacked in October for "suspected serious disciplinary violations".
The term typically refers to the corruption that has become endemic in China.
In China, expulsion from the ruling party is normally a precursor to criminal charges.