The 21-year-old won out ahead of England flanker Ben Earl, Ireland centre Bundee Aki and Scotland wing Duhan van der Merwe to become the youngest winner of the award and only the second Italian, after Andrea Masi won in 2011.
"This is a huge surprise and honour to be named the Six Nations Player of The Championship. It is truly special to represent my country, and to wear the Italy jersey alongside my friends and teammates," Menoncello said.
"To then deliver performances that hopefully inspired the fans is what dreams are made of. Winning this award is testament to the achievements of the entire Italy team, and a sign of the exciting journey we are taking with Italian rugby."
Menoncello was at the heart of Italy's most successful Six Nations campaign, as they secured wins over Scotland and Wales alongside a draw in France, forging an impressive partnership with Ignacio Brex.
He was also named in the Team of the Championship, along with Italy captain Michele Lamaro, in a side dominated by Six Nations winners Ireland, who had eight players chosen. France and Scotland had two players included, with one from England.
Team of the Six Nations Championship:
15-Thomas Ramos (France) 14-Duhan van der Merwe (Scotland) 13-Bundee Aki (Ireland) 12-Tommaso Menoncello (Italy) 11-James Lowe (Ireland) 10-Finn Russell (Scotland) 9-Jamison Gibson-Park (Ireland) 8-Ben Earl (England) 7-Michele Lamaro (Italy) 6-Caelan Doris (Ireland) 5-Joe McCarthy (Ireland) 4-Tadhg Beirne (Ireland) 3-Uini Atonio (France) 2-Dan Sheehan (Ireland) 1-Andrew Porter (Ireland).
7°C