The man was arrested at Milan's Malpensa airport last July and is "suspected of acting for the Chinese government", the police statement said.
He is accused of hacking US government entities, research institutes and universities involved in vaccine research in 2020 and 2021 at the height of the pandemic, the statement said.
The police did not identify the man but said he was a former head of a major technology company in Shanghai.
He is alleged, along with associates, to be behind a hacking group called "Hafnium" which was accused of penetrating tens of thousands of Microsoft Exchange email servers in 2021.
At the time, Microsoft called the group a "highly skilled and sophisticated actor".
Italian police said the suspect was arrested on a warrant from Texas, hailing an "excellent and well-established cooperation" with the FBI as a reason for the operation's success.
dt/sbk