The 27-year-old Georgia international defender has been allowed to leave Ewood Park after falling down the pecking order under Sam Allardyce.
Khizanishvili has made just one appearance for Rovers this term, with his only outing coming in the 3-1 Carling Cup success away to Gillingham.
Magpies caretaker boss Chris Hughton has swiftly moved to strengthen his defence after seeing the North East outfit suffer their first defeat of the new season at Blackpool on Wednesday night.
Hughton told the club's official website: "Zurab is an experienced defender and we're very pleased to get him on board.
"He knows English football very well and will be a valuable addition to the squad over the coming months."
Khizanishvili will go straight into Newcastle's squad for Saturday's Championship clash with struggling Plymouth at St James' Park.