The inhabitants of Sant'Agata de Goti in the mountains near Naples have been invited to an election party where they will follow the ballot counting on the other side of the Atlantic.
"We might stay up into early Wednesday to find out the result," said Carmine Valentino, adding: "The town council has already taken a decision to grant Mr. de Blasio honorary citizenship."
De Blasio, a 52-year-old Italian-American, is the Democratic candidate and is almost certain to win the vote, with the latest poll giving him a 41-point lead over Republican Joseph Lhota.
De Blasio's maternal grandfather came from the town, which has a population of 12,000.
"We consider him a fellow citizen here. He last came in 2010 with his family," a spokesman for the town council said.
"His choice to name his children Chiara and Dante shows his link with Italy. He really is a son of this land," he said.
De Blasio's cousins still live in the town.
The partying for his likely election will continue on Saturday with a feast in the town.