Borini, who was training with the Italian Under-21 side ahead of Friday's match European Championship qualifier clash with Sweden, went for an MRI scan on Thursday which revealed the injury.
The news will be a major blow to Liverpool boss Brendan Rodgers, who only has one recognised senior striker in Luis Suarez.
It is expected that the summer signing from Roma, who cost the club in the region of £10.5 million, will be sidelined for several weeks.
Though Borini has largely been used in a wide position since joining the club, his injury leaves Liverpool severely depleted in attack.
Suarez has performed in the central role this season, scoring seven goals in 10 appearances, but the decision to allow Andy Carroll to join West Ham on loan, coupled with a failure to sign Clint Dempsey on deadline day, means Rodgers lacks options.
Reserve strikers Dani Pacheco, Samed Yesil, Adam Morgan and Jerome Sinclair, the club's youngest ever player, could be in contention for a call-up.