The shortlist was compiled of winners of the RBS Man of the Match award from the first four weekends and the public were invited to vote for their choice on the official tournament website.
"It has been a Championship of highs and lows for the Italian team," said Masi.
"Our win against France will go down in rugby history but to finish sixth frustrated us all.
"However, to be named the RBS Player of the Championship is a fantastic way to end what has been one of the most competitive Championships I can remember.
"We have worked hard this year and can be proud of our achievements. Italian rugby continues to strengthen and we are very happy with our progress as a team. To be the first Italian voted to win this award by the fans is a huge compliment."
Masi secured just over 30% of the total votes whilst team-mate Fabio Semenzato came in second with just under 12%.
The Italian duo, were closely followed by Leinster's Sean O'Brien and Leicester Tigers playmaker Toby Flood.