3 Italia and Wind Telecomunicazioni have undertaken a €21.8 billion merger.
The pair will combine to create the largest Italian mobile operator with 31 million users.
The merger was initially announced in August 2015, but the merger clearance process with the European Commission was elongated by the greater scrutiny placed upon the European telecoms market following the blocked takevoer of O2 by Three in the UK.
The deal was cleared following divestments by CK Hutchinson and Vimplecom (the owners of 3 and Wind respectively) to French operator Iliad.