The newly-elected board of directors, including Descalzi and former tax police general Giuseppe Zafarana who was appointed chairman, was expected to meet on Thursday to formalise Descalzi's CEO nomination.
The manager is on course to become the longest-serving company head at state-controlled Eni since its foundation in 1953.
He has held the job since 2014, and last year helped the Italian government secure alternative gas supplies as Moscow curtailed its flows to Italy following Russia's invasion of Ukraine.
Around 77% of shareholders registered for the annual general meeting have voted for the nine-member board presented by the Treasury, which owns 4.4% of Eni's capital. Italian state lender CDP has another 26.2% stake in the company.
(Reporting by Cristina Carlevaro and Francesca Landini, editing by Alvise Armellini and Chizu Nomiyama)
