The 21-year-old joins the newly promoted Serie A outfit following a two-year spell at the Imtech Arena.
The Italy under-21 international failed to establish himself as a regular with Hamburg after moving from Chelsea in July 2011.
Sala will now link up with his new team-mates, who are tasked with keeping Verona in the top flight following their return after an 11-year absence.
Andrea Mandorlini has recruited heavily in the close-season, with veteran striker Luca Toni and experienced midfielder Massimo Donati among those to switch to the Stadio Marc'Antonio Bentegodi.
Sala made eight appearances for Hamburg last term.
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