The North Shields-born defender, who joined the Magpies' youth set-up at the age of 12, joined the Valiants on a season-long loan in July for the duration of the 2021/22 campaign, making his Vale debut against Sunderland during a Carabao Cup tie in August.
However, the 21-year-old - who helped Hartlepool United gain promotion from the National League last term during a positive loan stint in 2020/21 - will return to Tyneside after recently suffering two ligament tears in his ankle during a freak incident in training.
Capable of playing in the middle of defence as well as full-back, Cass made 27 appearances for the League Two side in all competitions this season, scoring his first ever senior goal during an FA Cup first round victory over Accrington Stanley.
Port Vale manager, Darrell Clarke, told the club's official website: "He has been outstanding for us, he's served the club with massive credit. The fans loved him, I loved him and we all wish him a speedy recovery."