Nearly 90 per cent of Capitalia shareholders approved the deal, while 99.86 per cent of Unicredit's voted in its favour.
The transaction will create an entity with a market capitalization of $110.64 billion, making it the second largest bank in the euro zone after HSBC.
Following approval from banking authorities, the deal now requires approval by Italy's antitrust authority, which is currently investigating competition issues in a domestic market recently marked by increasing consolidation.
The investigation hinges on Unicredit's acquisition of Capitalia resulting in it also inheriting a stake in Mediobanca, which in turn holds a stake in insurer Assicurazioni Generali SpA.
Unicredit hopes to seal approval by selling its stake in Assicurazioni by the end of year. Pending regulatory permission, the transaction will go through as of October 1st.