The Italian Football Federation (FIGC) said Spinazzola was diagnosed with "subcutaneous rupture of the left achilles tendon" when the 28-year-old Roma defender underwent medical checks at a Rome hospital.
Italy defeated Belgium 2-1 in a EURO 2020 quarterfinal match Friday as Spinazzola left the pitch in tears after the injury in the second half.
FIGC President Gabriele Gravina said he was "very sorry for Spinazzola" and that the defender gave his best to Italy.
"I wish him the best of luck for a quick return, because not only is he a great professional, but he has also shown great personal qualities," he added.
Spinazzola's return is uncertain.
He had two assists for Italy in four EURO 2020 matches.
Italy, without Spinazzola, will face Spain on Tuesday in the semifinal.
