The 21-year-old left the training track after going to ground in a tackle.
He underwent scans on Thursday afternoon, with results confirming the worst.
BREAKING: Shocking news for young Pie Jackson Ramsay. Scans confirm he has ruptured his ACL after innocuous training incident. @FOXFootyLive
— Tom Morris (@tommorris32) April 7, 2016
Ramsay has played nine career games, including the Pies’ thrilling win over Richmond on Friday night, where he took seven marks and finished with 23 disposals.
He was selected by the Magpies with pick No.38 in the 2012 National Draft.