The 20-year-old has been an integral first-team player for Atalanta BC this season, making 44 appearances in all competitions, and celebrated winning the Europa League earlier this month.
Scalvini started and scored a first-half goal in Atalanta's final Serie A fixture of the 2023-24 season on Sunday - a 3-2 home defeat to Fiorentina at the Gewiss Stadium.
However, the central defender was forced off in the 84th minute and was trying to hold back the tears after sustaining a knee injury when attempting to make a challenge.
Scalvini was initially included in Luciano Spalletti's provisional 30-man Italy squad for Euro 2024, but Atalanta have now confirmed that the youngster has suffered an ACL rupture to his left knee and is set for lengthy spell on the sidelined.
Italy without two key defenders for Euro 2024
A statement from Atalanta as quoted by Italian news outlet Gazzetta read: "After the match against Fiorentina - we read in the note - Giorgio Scalvini was immediately subjected to diagnostic tests which highlighted the rupture of the anterior cruciate ligament of left knee.
"In the next few hours the player will be subjected to further clinical-specialist evaluation to define the next suitable procedure."
It remains to be seen how long Scalvini will be facing on the sidelines, but the recovery time for a torn ACL is usually between six and nine months, meaning he could be ruled out until 2025.
Scalvini, who has earned eight senior international caps for Italy, is the second Azzurri centre-back to be ruled out of Euro 2024 in the space of just four days after Francesco Acerbi withdrew from the squad last Friday with a groin injury.
Inter Milan defender Acerbi, 36, was part of the Italy squad that won Euro 2020, but he has now been replaced in Spalletti's squad by Juventus' Federico Gatti.
Man United to cool interest in Scalvini?
Not only is Scalvini's injury a blow for Italy, but is may also come as a blow to Manchester United, who have been credited with an interest in the Atalanta man for some time.
Reports earlier this year claimed that the Red Devils have been in touch with Atalanta to discuss a possible summer move for Scalvini, who is valued at around €39.7m (£34m) and has a contract with La Dea until June 2028.
However, the long-term injury suffered by Scalvini could now see Man United turn their attention to other defensive targets, with the addition of at least one centre-back high on Erik ten Hag's list of priorities.
It is understood that Everton's Jarrad Branthwaite is one of Man United's top targets, while they have also been linked with the likes of Nice's Jean-Clair Todibo, Chelsea's Trevoh Chalobah, Barcelona's Ronald Araujo and Benfica's Antonio Silva.