The move comes after Telecom Italia said earlier on Monday it was in "advanced negotiations" on Patuano's resignation.
After weeks of speculation, investors seemed to welcome the statement, with shares in Telecom Italia trading 3.1 percent higher in early afternoon business on the Milan stock exchange.
The announcement follows reports in recent weeks of Patuano's possible departure as well as of bad relations between him and chairman Giuseppe Recchi.
Recchi could assume the helm in the interim, Italy's AGI news agency reported.
The AGI news agency also said that Patuano's recent visit to Vivendi's Paris headquarters apparently accelerated his exit from the company with the French firm calling for a "discontinuity" in Telecom Italia's management.
Vivendi owns nearly a quarter of the Italian operator.
Other media have also reported on differences between Patuano and Vivendi.
According to the online version of financial daily Il Sole-24 Ore, Vivendi asked Patuano for spending cuts that went deeper than the €600 million ($675 million) for 2016-2018 that the chief executive already had planned.
Telecom Italia posted a net loss of €72 million last year after a profit the previous year of €1.35 billion, while sales dropped more than eight percent.
Media reports say that among his possible successors is private rail transporter NTV's Flavio Cattaneo.