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.
‘Even though it was late in the game, the Arsenal fans started singing my name. It felt like the moment I announced myself as a professional footballer’: Ex-Gunners star recalls scoring first senior goal as a teenager at Highbury
'I started to drive myself crazy': Former Manchester United midfielder explains why it all went wrong for him under Erik ten Hag
